[10.2 regression] CKEditor 5 breaks when "Source"/Source editing button is added and "Manually editable HTML tags" are specified

Problem/Motivation

CKEditor breaks when "Source"/Source editing button is added and "Manually editable HTML tags" are specified

Steps to reproduce

1. Define text format
2. Enable some of the buttons / features
3. Enable "Source" button
4. Save text profile and it works
5. Now edit again and add some "Manually editable HTML tags" in the "Source editing" plugin settings
6. One can't save profile settings with error "The current CKEditor 5 build requires the following elements and attributes: LIST OF SOME TAGS The following elements are missing: LIST OF SOME OTHER TAGS"

Additionally, this happens if such text format was specified in 10.1.x, where this worked perfectly, but once updated to 10.2.x, pages using text format using source button with manually editable HTML tags will break with tags listed under LIST OF SOME OTHER TAGS" will not render and the pages look broken