the app is pretty much perfect i would say for mullvad, i basically never have had any issues with it..
rarely there are connection problems but they usually resolve themself quickly (but this could also just be normal wlan issues)
The downside is, that i think it is more often that sides are blocking/ require a login in. In particular reddit sometimes, and youtube basically always.
For reddit i consider it a feature currently to be honest.. since it blocks me from using it
That beeing said, i basically did also switch from proton to mullvad+ tuta like a few months ago, and i dont regret it.
The only issue is, that like tuta doesnt has that many alias addresses... but there is not really any good solution for this at all