UWSGI conf not working anymore

My previous installation of mat2-web were smooth, but we are several to have the same problem on a fresh debian buster install, following step by step the mat2-web README.

During the uwsgi start, there are theses logs :

unable to find "application" callable in file /var/www/mat2-web/main.py
unable to load app 0 (mountpoint='') (callable not found or import error)
*** no app loaded. going in full dynamic mode ***

All requests will result in a 500 error, with a no python application found log line. Launching manually uwsgi does the same. Modifying the app code the replace "app" by "application" doesn't work too. Internet didn't help much.

Just launching the app with python works well.

It seems uwsgi is quite capricious. Maybe we should think about replace it by something else more reliable ? (Gunicorn ?)