After years of using Flutter I don't know if I have any pain points anymore. I'm not saying it's perfect (far from that) but it's because I'm already used to the annoyances it might cause.

When I first started using it, I used to complain about the Dart language. I really liked Kotlin and I kept asking why didn't they go with it but, a few weeks later, I was already proficient in Dart and never looked back (to Kotlin). Today, Dart is one of my favorite languages together with Go and C, and I even bought the domain name dart.rocks :). I might do something with it later this year.