Do you see a magisk related file in system/addon.d ? Maybe it survived your purge.I did dirty flash and strange thing occurred: In apps I found Magisk Manager but I didnt installed this before. v7.2.0 After opening it wants to install full version omitting Play Store (it asks for permission to install from unknown sources). What's happening? Is it bundled in last version of LOS?
Once I had flashed Magisk but i purged it month ago and it was different version.