The best I’ve seen was yesterday where a website had the log-in button greyed out after the password manager filled my creds in.
So I had to manually clock both the email and password field. Just click them. Then it enabled the log-in button.
So someone took their time to write a piece of JS that said “If the user hasn’t focused both fields at least once, no login”. Literally why? Extra code that does nothing useful.

I was hoping passkeys would be the solution to this madness, but it seems to me the entire spec gives too much power to the OS Makers and too little to the users because “mUh AtTtEsTatIoN” so now I don’t know anymore

I’ve definitely run into that. Even more frustrating is when there was one particular site that forced me to actually delete the last character of my password and then retype it. Just focusing in the field wasn’t enough, I had to actually send it a keystroke. And Ctrl-V to paste the password in manually didn’t count. I suppose typing a random character at the end and then deleting it would have worked too.