Tried update via magisk manager. First update the manager. Then update magisk root via magisk manager. It failed to download something. When I rebooted it was only in fastboot mode. Tried to boot to recovery to uninstall it / install the zip file. whatever I did, I got stuck with errors. I gave upDid it erase your apps & data? What steps did you take?
I used 10.3.6-OnePlus6TOxygen_34.J.48_OTA_048_all_2010042240_dbd576b615-FASTBOOT
I had it hidden. But I restored it before upgrading. But I did not reboot the phone after restoring it... Before upgrading. It may be the reason.. I don't know...The people it failed for, you hadn't hidden the Magisk Manager app right? Because you're supposed to restore the app before updating to 22.