Bought a managed device - automatically resets

I bought a used Google Pixel 3 XL from a marketplace website. Everything seemed fine, until I started getting a notification saying “Device managed by admin - Automatically resetting soon".

When I tap on the notification, it says “Device setup keeps stopping". I checked the phone's IMEI on the online blacklist, but it doesn't classify as lost or stolen. If I try to factory reset the phone, it asks me for an "@google.com" adress.

My question is, should I be worried? Is there a way to fix this?