looks like rendering adblockers extensions obsolete with manifest-v3 was not enough so now they try to implement DRM into the browser giving the ability to any website to refuse traffic to you if you don't run a complaint browser ( cough...firefox )
here is an article in hacker news since i'm sure they can explain this to you better than i.
and also some github docs
What's the replacement for Android?
Linux, but that's not a viable option. I would use degoogled Android OSs. GrapheneOS, CalyxOS, e/os, and LineageOS are some of the popular ones.
I use SailfishOS and while it's more work, it's viable.
Also correct here.
The 3 main have varying degrees of function vs security/privacy and should be researched.
Android, but the real one (AOSP, etc) that you can get with custom ROMs, not Google® Android©.
AOSP is a Google product.
That¿s why I said "the one you get from the custom ROMs". Well, the ones that fork and maintain on their own anyway.
The other alternative honestly is Linux mobile, once it more properly launches.
Look, it's an unpopular opinion and many will disagree with me, but while Apple does certain things to restrict you from customizing your experience, they're doing far less to destroy the open Internet than Google. So if you need a fully featured OS (which degoogled custom Android ROMs might not be, if you need banking for an example), it's still an alternative for now, until Linux mobile experience gets better.
On iOS, there's no browser extensions (for e.g. ad blocking), no alternative browsers, and no FOSS apps of any kind. That platform is extremely hostile to the ideals of computing freedom.
Like I said, it's a better (for privacy) alternative to stock Android when you need a fully functional operating system. If you can stand to lose the oppressive Google functionality, you can go degoogled Android or preferably Linux (if you don't care about battery life or app availability).