Here are some screenshots of the visual glitch:
You can see that the quotation mark and the > overlap for all tags.
I am on Developer Edition, Mozilla Firefox 122.0b3. The same issue is in non-developer version. I am also on Arch Linux.
I fixed via https://www.reddit.com/r/FirefoxCSS/comments/73dvty/tutorial_how_to_create_and_livedebug_userchromecss/
Can you pelase share what rules you have added to your userChrome css file?
On my Debian Linux I don’t have an issue… unless I change the font for monospace text in about:preferences to a non-monospace font. In that case I can reproduce the issue, and it seems to come from the styles for .newattr.
Can you please file a bug to https://bugzilla.mozilla.org/enter_bug.cgi?product=DevTools&component=Inspector with all the things you did to make this bug appear, and then fix it?