https://www.androidpolice.com/2020/11/03/gboards-voice-dictation-is-now-powered-by-google-assistant-for-some-users/

Dunno how much it affects what you're trying to do, but I thought I would pass it along.

Be happy that you're not trying to use multiple languages, I guess?

https://www.androidpolice.com/2020/11/03/voice-input-on-android-is-a-multilingual-mess/

Good luck!

Cheers,
Scott.