User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:89.0) Gecko/20100101 Firefox/89.0

Steps to reproduce:

Updated to Firefox 89.
Opened a few tabs.

Actual results:

I was having a hard time switching the tabs because there is no separator between tabs.
Or:
Iwashavingahardtimeswitchingthetabsbecausethereisnoseparatorbetweentabs.

Expected results:

"|" should have happened between the tabs.
Attached is screen capture with how the separator looks on Chrome or Edge.
I'm not sure if this is a "design" intent in Firefox 89 but it seems to be a bug.

The Bugbug bot thinks this bug should belong to the 'Firefox::Session Restore' component, and is moving the bug to that component. Please revert this change in case you think the bot is wrong.

I think this bug has been inappropriately marked as duplicate.
While one bug is dealing with changing the colour contrast, the other is dealing with the missing separator. Unless the bar is really the very same colour with the background I would say the separator is missing.
This might be the design intent, and I learned my protest is futile but if this is the case the bug 1717750 should be closed as "Won't fix" rather than duplicate of fixing something else.

The attachment https://bugzilla.mozilla.org/attachment.cgi?id=9225430 show both issues:

one can assess the contrast of icons and ask for improving the contrast.
one can observe the missing separators - unless is a "no contrast whatsoever" separator - and ask for bringing back the separators.

So, is the separator coming back?