Hello,
I hadn’t even thought to check here but I have the exact same issue. Everything thing works fine for a while but with both sides switched on, after a little bit there is a very significant drop in volume and quality (unusable)

Playing at home is a fairly simple fix, just switch it on and off.
Disastrous at a gig though and it makes the pedal unusable in any band situation.

Clearly I am not the only one having this issue
How do I fix this?

I am in Australia.

Thanks