I’d guess Search is pretty well segregated from basically everything else because of how valuable it is - I’m logged into Google on Search and it works fine (unlike everything else)

Search works for me but it thinks I’m logged out - it just prompted me with the 'please agree to our T+Cs' dialog.

It looks like it is related to authentication, landing pages seem to be working, so going incognito you can still use youtube.

I would guess the search page does not actually use your credentials for anything since fingerprinting is separate from login?

I would've thought Google remembers what you search while logged in and sells it off. Maybe they do it in a different way - never really thought about that. I'm logged into Google when I search but my profile fails to load at the top right.

They probably do, but it is not essential to the functionality so it can work even if auth fails.

Fingerprinting happens separately because then they can identify you even if you are not using your own computer or are in incognito. Login is just a convenient way for you to tell them who you are.

It is something related to authentication. Even YouTube works without being logged in

When logging into any of my gmail personal/free and corporate paid for accounts i get "Couldn't find your google account" in red writing

Google Search Images doesn't work either: https://www.google.com/search?q=random&tbm=isch&source=lnms

Google search was slow for me during the outage (5-10s per request)

I imagine google search only has optional dependencies on login and correctly falls-back if these fail

Probably something related to users authentication then