I built an app that is running mainly in a Samsung tab A7 lite. The app itself is pretty simple, no internet connection, only uses a local SQLite, no complex operations, no custom animations, but the performance is shit, its usable, but there is clearly a lag. Though testing it in my phone (Redmi Note 10, not high-end at all) I have no problems with performances.

I've used very low-end devices with no lag, so this is surprising. I've always had more consistent performance in flutter, and the smoothness is usally what tips me off. React Native tends to be very fast though, since it uses native views.