The utter user-interface butchery happening to Safari on the Mac is once again the work of people who put iOS first. People who by now think in iOS terms. People who view the venerable Mac OS user interface as an older person whose traits must be experimented upon, plastic surgery after plastic surgery, until this person looks younger. Unfortunately the effect is more like this person ends up looking… weird.
These people look at the Mac’s UI and (that’s the impression, at least) don’t really understand it. Its foundations come from a past that almost seems inscrutable to them. Usability cues and features are all wrinkles to them. iOS and iPadOS don’t have these strange wrinkles, they muse. We must hide them. We’ll make this spectacular facelift and we’ll hide them, one by one. Mac OS will look as young (and foolish, cough) as iOS!
I haven’t encountered a single person who likes the new Safari tab design on macOS.