Google laid off the Flutter team. They still seem to be releasing Flutter announcements but it's slow.

One big part of Flutter was that it was a hedge against Java lawsuits back in the day. The other was that it was experimenting with some mobile code, like designing it around lifecycles and all the async UI. But now the same paradigms have been adopted by iOS and Android.

Unlike BE, mobile moves quite quickly too; the last few years have been deprecating a lot of things like push notification security and file access. Mostly to deal with dark patterns. So a platform that isn't in active maintenance tends to fall apart quickly like we've seen with many mobile libraries, Cordova, etc.