Here’s the issue we’re using to track this: https://github.com/home-assistant/core/issues/56044
It’s actually a problem with Growatt itself, we don’t know why but a load of the API calls have stopped working in the library that we use (and I co-maintain) the ticket for that library is here: https://github.com/indykoning/PyPi_GrowattServer/issues/16
I’m going to try and take another look at it tonight once I’ve finished work, but we’re beholden to the Growatt server, looks like they may have deployed an update and it’s broken the way we interface with it.