Hi

The tab bar has not moved in this update and has been where it is now for many years, so I am not sure what you mean.

Have you used a custom unsupported alteration to move the tab bar in the past?

The location is not my issue. The tab bar is wider and the tabs are less distinguishable than before. The previous design was better and took less space at the top of the screen.

Hi

I am guessing that this is the first time you have updated in a few months

This is the new interface to Firefox. Outside of different colour themes that may help, I am not aware of any officially supported ways to change the design.

Firefox has a Compact density option which makes all of the toolbars shorter (tabs bar, main toolbar, bookmarks toolbar). You could give it a spin and see what you think: Compact mode workaround in Firefox.

But there isn't any built-in feature or add-on to restore boundaries between tabs. If those are essential for you, then you would need to delve into the world of unofficial style hacks, through a userChrome.css file. If you'd like to learn more about that, I have a site with information:

https://www.userchrome.org/firefox-89-styling-proton-ui.html