Qt costs serious money if you go commercial. That might not be important for a hobby project, but lowers the enthusiasm for using the stack since the big players won't use it unless other considerations compel them.

...which is the same as Flutter. Both don't use native UI toolkits (though Qt doesn't use Skia, I'll give you that (Flutter has Impeller engine in the works)). And Qt has much worse developer experience and costs money.