Thanks for the quick response!
I'd already found the button, but it's quite a fiddly process to find it. It'd be easier if there was an option so that when you pressed the EQ button in the bottom bar it took you directly to to PA EQ app.
For now, I'll probably just keep the two EQ settings separate.
Sadly, flipping that setting for the Bandcamp app doesn't fix the issue. I also tried the multi-session option -- no difference either.
FWIW, Podcast Addict doesn't have the stutter problem, so it must be an interaction with the Bandcamp app.