How can I stop the full HTML editor from deleting my  paragraph? https://drupal.slack.com/archives/C1BB308HH/p1602318464360700 Link to slack question in #support
JSFiddle of the offending html: https://jsfiddle.net/tyeth/xr4ohast/
Demo Video showing the paragraph beneath second image being removed: https://www.youtube.com/watch?v=Hw9NACmMsps [Was private, now just unlisted, sorry]
Hi supportive people, you must get this one a lot. I'm aware of the filter options and have customised the Full-Html mode to not use the 3 offending filters, and cleared cache, but I'm still losing content.
I'm using the drupal 8(and 9) add a custom body block using layout designer, I then use the WYSIWYG editor in full-html mode with the filters (strip bad html/convert newline br+p/convert images -- see screenshot) disabled.
However it is DELETING html from the end of the editor. I wonder if it's technically an empty paragraph as that has been mentioned in other issues (it isn't but has a link inside so doesn't have it's own text content).

Also, which module is actually doing the rich editing these days?
Could be related to the auto paragraph funcitonality of CKEditor, which is used by default and can be disabled with this !deprecated setting:
&quot;autoParagraph = false&quot;

This can be easily disabled using the ckeditor_config module, see https://www.drupal.org/project/drupal/issues/3131055 for more information.
The whole paragraph wrapping in CKEditor is kind of buggy, you could also try these patches: https://www.drupal.org/project/drupal/issues/2876094 (but there the problem is an added p after an img)

I had some troubles when using linkit: https://www.drupal.org/project/linkit/issues/3162596 and made this core issue https://www.drupal.org/project/drupal/issues/3162605 (this is not related to your problem as your using the align and caption filters - but you see where the magic happens - on Drupal side).