There's a handful of phpcs issues to be fixed.
phpcs --standard=DrupalPractice --extensions=php,module,inc,install,test,profile,theme,css,info,txt,md,yml core/modules/comment
FILE: /Applications/MAMP/htdocs/drupal-9-dev/core/modules/comment/comment.module
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FOUND 0 ERRORS AND 3 WARNINGS AFFECTING 3 LINES
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222 | WARNING | There must be no blank line following an inline comment
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FILE: /Applications/MAMP/htdocs/drupal-9-dev/core/modules/comment/src/CommentTypeForm.php
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FOUND 0 ERRORS AND 10 WARNINGS AFFECTING 10 LINES
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78 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
96 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
97 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
112 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
114 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
121 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
128 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
148 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
163 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
168 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
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FILE: /Applications/MAMP/htdocs/drupal-9-dev/core/modules/comment/src/CommentTypeListBuilder.php
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FOUND 0 ERRORS AND 2 WARNINGS AFFECTING 2 LINES
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32 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
33 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
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FILE: /Applications/MAMP/htdocs/drupal-9-dev/core/modules/comment/src/Entity/Comment.php
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FOUND 0 ERRORS AND 2 WARNINGS AFFECTING 2 LINES
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113 | WARNING | There must be no blank line following an inline comment
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FILE: /Applications/MAMP/htdocs/drupal-9-dev/core/modules/comment/src/Plugin/Field/FieldWidget/CommentWidget.php
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FOUND 0 ERRORS AND 8 WARNINGS AFFECTING 8 LINES
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32 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
36 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
37 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
38 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
41 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
44 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
47 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
56 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
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FILE: /Applications/MAMP/htdocs/drupal-9-dev/core/modules/comment/src/Plugin/Field/FieldType/CommentItem.php
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FOUND 0 ERRORS AND 13 WARNINGS AFFECTING 13 LINES
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111 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
113 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
117 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
125 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
128 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
129 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
130 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
136 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
141 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
144 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
145 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
146 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
188 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
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FILE: /Applications/MAMP/htdocs/drupal-9-dev/core/modules/comment/src/CommentForm.php
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FOUND 0 ERRORS AND 2 WARNINGS AFFECTING 2 LINES
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82 | WARNING | \Drupal calls should be avoided in classes, use dependency injection instead
384 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
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FILE: /Applications/MAMP/htdocs/drupal-9-dev/core/modules/comment/src/CommentStorage.php
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FOUND 0 ERRORS AND 1 WARNING AFFECTING 1 LINE
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160 | WARNING | There must be no blank line following an inline comment
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FILE: /Applications/MAMP/htdocs/drupal-9-dev/core/modules/comment/src/CommentLazyBuilders.php
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FOUND 0 ERRORS AND 5 WARNINGS AFFECTING 5 LINES
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173 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
180 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
186 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
197 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
209 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
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FILE: /Applications/MAMP/htdocs/drupal-9-dev/core/modules/comment/src/CommentTranslationHandler.php
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FOUND 0 ERRORS AND 1 WARNING AFFECTING 1 LINE
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33 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
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FILE: /Applications/MAMP/htdocs/drupal-9-dev/core/modules/comment/src/CommentStatistics.php
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FOUND 0 ERRORS AND 2 WARNINGS AFFECTING 2 LINES
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166 | WARNING | t() calls should be avoided in classes, use \Drupal\Core\StringTranslation\StringTranslationTrait and $this->t() instead
182 | WARNING | \Drupal calls should be avoided in classes, use dependency injection instead
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