Doubtful. My guess would be more so some sort of cookie fingerprint and A/B testing.

Oh duh, you’re completely right. My morning coffee hasn’t kicked in yet and I’m still waking up. That’s weird that it’s affecting logged out users. It could still be another experiment they are running. Wouldn’t surprise me at this point.

Mentioned in another comment, but they were running an experiment on a subset of users. They may still be doing it and cycling users or may have stopped it.

They were running an experiment of some kind on a subset of users. You were one of the unlucky ones.