Zoom low quality, bad audio, iOS Bluetooth-speaker

When listening to a Zoom-meeting with a bluetooth-speaker on iOS (iPhone), audio sounds very low quality like an old telephone.

On a desktop it also sounds bad initially, but there is an option to manually choose the internal mic so that high-quality audio is restored to the speaker.

Also there’s no option to use a speaker via an audio adapter. It simply doesn’t work. 
 

When will this be fixed? It works badly like this for years. Only iPhones internal speaker sounds good.