On my OnePlus 6T phone with Android 11, I have side loaded Kodi 20.x a few times and it has always updated to 21 (Omega) within a couple days.
Google Play: auto update OFF always.
Kodi: add-on auto update OFF.
Version check add-on: setting to not update. I’ve also tried disabling this add-on.
Note that the last few times I’ve done the install in airplane mode and disabled add-on auto updates (and the above version check settings/config) before reconnecting to data.
How can I stop this update? I don’t know where it comes come or how. No app on my phone auto updates except this.
Note that my Nvidia Shield Kodi 20.x behaves as it should, that is, no updates done behind my back.