Adaptive icons only seem to be used by the default Google launcher (and on my new Pixel 4a with Android 11 it looks as though a lot of the Google apps, Docs, Gmail, Play Store and others don't have an adaptive icon!). It looks to me like yet another feature that Google added thinking it was "a good idea at the time" and then subsequently ignored in practice.
I always use Evie launcher for consistency across all my devices and standard .png icons whatever their size, render fine. If you can't render an adaptive then how about at least adding the file name to the menu item so I know which icon is selected. Ironically Evie itself does seem to have an adaptive icon.
