While we're talking about Safari, it also developed this bug where picture-in-picture leaks memory like crazy where it sometimes consumes over 80GB of RAM, gets compressed to nothing but freezes the app to the point where I cannot type anything in the address bar.

That's where the WebKit previews come in handy, if you stick to a preview version you know matches a stable version.

Certain features are not supported unles you're on MacOS 26, period, even with Safari TP

Oh, interesting! Which features?