When composing a new email using the included CKEditor5 interface, new paragraphs do not have any margins and appear the same as line breaks. This is confusing for end users, as the email will look different when sent.

Essentially pressing "Enter" and "Shift+Enter" looks the same when writing the email.

The issue is likely a CSS override somewhere that sets the margins of paragraphs to 0.
The issue only appeared after the recent update that included CKEditor5.

When inspecting a paragraph in the editor, the snippet included in the attachments shows the margins of paragraphs are set to 0.

As a workaround to "fix" the issue we added a custom CSS override at the end of the theme-default.css file located here "/var/lib/docker/volumes/mailcowdockerized_sogo-web-vol-1/_data/WebServerResources/css/theme-default.css":

.ck-content p {margin: revert;}

After that paragraphs in the CKEditor5 have the correct spacing and look like you would expect.
See the attached screenshots for a before and after. You can see the correct spacing between parapgrahs after applying the fix.