Indeed, and I was talking about the boot image, but some still refer to it as the recovery, i.e. LineageOS. I see LOS have changed their download pages now and correctly call the boot image boot.img instead, that's good. So anyway, just download the boot image alongside the ROM instead of extracting it, and rerun Magisk install before rebooting after an OTA, and it's all very doable. Not as easy as before, but not too hard either.
LineageOS seems to make a name change just now with the boot and recovery thing. For reference, https://topjohnwu.github.io/Magisk/install.html is what I reference. The file you get instructed to path is the boot.img. Note how "you have to do something after every ROM upgrade" does not get mentioned - so it is a little bit better than I thought if Magisk has an action in the app that can be run before the reboot, but that's still way too brittle to be useable.
(I vouched for your comment, it was hidden, that's normal for new accounts.)
