It seems that the OS is deleting(?) TWRP.
After successfully booting the OS, I wanted to boot into recovery through the extended reboot, but the smartphone was then in fastboot mode.
What I did:
- Updated TWRP via TWRP to twrp-3.6.1_9-0-raphael.img
- Wiped: Factory Reset & Format Data (filesystem was ext4)
- Updated EU firmware via TWRP (fw_raphael_miui_RAPHAELEEAGlobal_V12.5.1.0.RFKEUXM_dd92b7128a_11.0.zip)
In each case I could still restart to TWRP.
- Finally, flashed Nusantara-v4.4-12L-raphael-07042022-OFFICIAL-1831.zip
Another problem was that there is no package installer (com.android.packageinstaller) with which I could install e.g. F-Droid.
A non-Gapps variant might be interesting for others as well. With microG as an example.