What is the reasoning behind Stackoverflow login fragmentation?
Why does each of the stackexchanges keep asking to sign up and login again?
Is it due to have an account with zero reputation to begin with in each of the sub_overflows?
A lot of them use separate domains which makes it hard to share cookies. The actual login credentials work across sites though - so a login from StackOverflow will work on ServerFault (although it will create you a new site-specific profile with zero reputation and privileges, as those are per-site).
No idea, I'm just happy that I don't need to go there any more. A few great contributors, but not worth the 20:1 s:n ratio.
It sounds like they are descending into chaos after GPT consoomed all their precious tokens to train a replacement of it.