Problem/Motivation
Drupal 8 is running on CKEditor 4.x. CKEditor 5.x has gone stable and looks like it has enhancements to help improve the authoring experience.
CKEditor 5 also no longer relies on inline JavaScript, which requires a more permissive Content Security Policy due to its use in CKEditor 4 (#2789139: [upstream] CSP requires 'unsafe-inline' because of CKEditor 4).
Proposed resolution
Upgrade CKEditor in Drupal to 5.x.
Remaining tasks
TBD
User interface changes
TBD
API changes
A migration guide has been provided from migrating from 4.x to 5.x, covering plugins, skins, and APIs:
Data model changes
TBD