Recently Google have started implementing hardware backed attestation of SafetyNet, so the previous
workarounds (e.g. just enabling Magisk Hide) no longer work.
For those running stock ROMs, you'll just need to install the Universal
SafetyNet Fix Magisk Module by kdrag0n, and reboot. You may have to clear the app data for Google Play
Service and make sure you have the appropriate apps hidden with Magisk Hide as well.
The default apps that Magisk hides already when you first enable Magisk Hide should be sufficient
(Google Play Services & Google Pay), but you'll need to add in any other apps that you need to hide root
& signs of a modded device from as well (e.g. Pokémon GO, Ingress Prime, Snapchat, your other banking
apps, etc.).
If you're using a custom ROM, you'll also need to change your device's fingerprint to match one that is
officially being used by Google Play certified devices. You can use the 'MagiskHide Props' Magisk Module
and follow the prompts to change your device's fingerprint to one that looks official. It's probably good
to choose the same device model that you're using.