Comment by notpushkin

Okay, I am pleasantly surprised. The fix was to... remove Magisk. Apparently they’re not looking at the Play Integrity, so no workarounds needed. The more you know!

This is way offtopic, so I’ll stop here, but final note in case anybody is looking to get Play Integrity working as well: try the built-in microG implementation first, and if it doesn’t work, go for KernelSU, it seems more stealthy than Magisk. Good luck!