It’s using an EOL version of python. Keeping it up to date to use at bare minimum a version that isn’t EOL (even if it isn’t the latest version) would be nice. Heck, I’d happily pay periodically for major updates since I’m not expecting free work for a product I value and paid for in the first place. It’s a fair criticism if an app is part of an evolving ecosystem (eg, python) and just stops keeping up: slowly but surely it skews further from what people are expecting, what practices are currently in use and those that have been abandoned by the community, etc.
What I don’t understand is why people who have popular apps and decide to stop working on them don’t sell them so someone else can keep them alive. Pythonista is awesome, and lots of people use it. I’m sure someone out there would happily step up to help keep it alive or take it over.