[F-Droid, version 2.4.0] Speech output does not work

When I upgraded from Android 10 to Android 11, speech output stopped working in this app. Other apps (e.g. OSMand navigation) still have working speech output, but Feeel does not.

(I'm on LineageOS 18.1/Android 11 on a OnePlus 5, without GMS, but I do have Google TTS installed and working.)

I should add that even it was working, speech output was a bit janky: I have my phone set to a German locale, and the TTS would (apparently) use an English voice to pronounce German words.