Yup, very first A12 release previews worked w/ Magisk on some (many?) devices before John made
any changes for compatibility!...
When moving to a different desert (Android version) previously, Magisk had often spat it out until it grew up a bit / a taste was acquired, so this was a bit of a fluke & surprised even John...
Since then various fixes have been made for proper Android 12 compatibility, eg:
Support code injection on Android 12,
boot image header v4 - supports brand new devices launched with Android 12 w/ v4 boot images),
Target SDK 31 - This is the main reason for note in change log; - proper API (Application Programming Interface) Level 31 (Android 12) support.
Note: all the above ([General] Support Android 12) fixes arrived with the first Canary Magisk not synced w/ 23.0 back in October, ie. 23010 (many fixes since then too). The last 2 were authored by vvb2060 and were available in her Alpha builds months before that too!
PW