On Android (and iOS / Mac Catalyst) the app icons are not actually added to the manifests because that code was not written.

For some reason I had determined that people would always use the same filename and thus the templates would be good - and somehow knowledge would arrive in the brains of devs to go change values in the platform files when editing the csproj.

This was obviously wrong and even though the docs are technically incorrect because they do not state that you have to change values in the manifest.

For backwards compatibility - and for explicit control - the manifest always wins, but if there is no icon in the manifest, the generated icon needs to be inserted.