well you have root duh lol, off course otas will fail, at least they dont install unlike old times when install would be error
there are many ways to install but this is the easiest for me every month
each month download full system image
copy boot to phone and patch it with magisk apk, copy back to pc
apply full system image flash all.bat but remove the -w from the .bat (Edit the bat)
this will install the lastest ota but you wont lose any data or settings, everything well be okay
root is lost, now you have to root again
boot magisk boot image
apply direct install in magisk apk
restart
this has to be done every month
you can also uninstall magisk every month and let the ota download and install but that is even slower and annoying, this is how is done