Yes, ironically enough, Safari 15.0’s diabolical tab styling (and Gruber is 100% right about how poorly designed they are), has made me consider using, erm, Safari instead of (or side by side with, maybe) Firefox. After seeing what all the fuss was about, I found out you can turn off the absurd shove-everything-into-the-tab-even-the-address-bar-and-make-each-tab-a-different-colour UI so it remains usable.
The very good thing about Safari is it’s nativeness. It looks and feels right on MacOS, and you get the share icon.
Firefox has also decided to make tabs not like tabs, going for what I call the lozenge look.
Decided not to in the end, though. Firefox has better privacy options and some killer extensions that I couldn’t do without, especially Stylus and Hide Fixed Elements. And we need to support the independent browser.