As I said before, this happens only with Bannerlord. After the last update that I installed, I had no sound from my TV when starting Bannerlord. This doesn't happen with other games that I play on the same console connected to the same smartTV as it always is. Everything else has sound, the Xbox menu, other games, other apps.
The TV's audio settings are on default. I have never changed them. And the audio works for everything else except Bannerlord, and it did work for Bannerlord in the past, having the same settings as now.
That's why this makes me think that, most probably, the problem is with the game, Bannerlord, itself.
As much as I like Bannerlord, and I can get past other bugs, or crashes, I can't play a game without audio.