Apologies, I misread that. I don’t have this issue on my iPad running 17.0.1. Neither in English, German, nor Spanish. Dictation is pretty quick for all three languages. It is a really strange issue to only happen in one language. I have no idea what you could try to fix this other than resetting the iPad.
As someone commented already you can use a personal automation to trigger when you leave a specific location. In case you are using a focus mode for work (which can be location and/or time based) you can use the activation and deactivation of this focus mode to trigger an automation as well!