I’m never updating the app until there is a good workaround.
Discussion
In two months your TestFlight version will expire. We have until then to figure this out.
64 days to be exact 😉 
I’m not on TestFlight. I just turned off automatic updates in my settings and am using an older official release.
Is there a way to downgrade outside of TestFlight or is it too late?
I’m not sure. Back in the day (2012-2015) there was a way to do this for most if not all iOS apps, but unfortunately it seems like the walls of the garden have gotten higher since I last looked into it.
Making an even stronger case for me to run a degoogled Pixel. Whew.
Just did some (light) research and my memory was correct, this ability was kneecapped when Apple got rid of iTunes. iTunes used to be used to manage all updates and data on an iPhone (since iPhones originally came from iPods) but they never replaced some of its functionality when they made it obsolete.
It seems like it’s not entirely impossible currently, but you’d need the right files and the software which claims it would do it looks sketchy at best. I’m not going to investigate any further as it’s above my level of technical knowledge or desire. Hopefully there will be a solution or resolution so new users can experience zaps soon ⚡️