Beosound A1 2nd gen: sound quality SUDDENLY bad

The sound quality on this speaker is usually great, but there are stretches of time where it suddenly, for no reason, starts to sound like it's a low quality car speaker with something blocking it. Like really muffled and lacking definition.

I have tried:

• charging the battery fully

• turning it on and off again

• turning my Bluetooth on and off again

• adjusting sound settings

• disconnecting and reconnecting

• refreshing app

Nothing seems to do anything. The lengths of time it does this is increasing, and I would really like help. Has anyone else experienced this?

I've only had this speaker for 1 month.