Software tamperproofing. Or, at least an attempt to it. Apps can request the info from Android: "hey, is this a legit Android system? Everything in factory condition?" and this mechanism would respond. Some apps request this in the name of security. In an attempt to ensure that the user and their data via the app are safe.

Normal, unmodified Android systems report back that they are untouched. The system detects LineageOS, /e/OS, Graphene etc as modifications though, so then it reports that the system is compromised. As an option, it can be hacked, so it reports A-OK even on a modified phone - but this hack is prone to breaking, and not the easiest to do to begin with.

It's not straightforward which apps need this thing. I found a compilation here:

https://xdaforums.com/t/apps-games-need-pi-list.4677050/

But the list has YouTube, and I can report that I'm happily using that for years on a phone without this mechanism, so, I cannot vouch for this list.