All recent failures are on Firefox and for the same reason:

Unexpected content: <p><strong>bolder</strong> <em>italic</em> <ins>underline end</ins><br></p>

"end" is inside underline style.

at org.xwiki.realtime.wysiwyg.test.ui.RealtimeWYSIWYGEditorIT.applyInlineStylesOnTheSameParagraph(RealtimeWYSIWYGEditorIT.java:563)

See https://ge.xwiki.org/s/gjt7p7ithnd22/tests/goal/org.xwiki.platform:xwiki-platform-realtime-wysiwyg-test-docker:failsafe:integration-test@functional-tests/details/org.xwiki.realtime.wysiwyg.test.ui.AllIT$NestedRealtimeWYSIWYGEditorIT/applyInlineStylesOnTheSameParagraph?expanded-stacktrace=WyIwIl0&top-execution=1

The problem is around the time we remove the underline style and type " end". It seems the caret remains inside the underline style on Firefox.