Vetted is another word for trust. Honestly, this kind of thing makes me want to NEVER trust these types of apps stores. Download from source and verify the gpg keys if at all possible. I've used flatpaks for a while but never for anything bitcoin or serious. You are trusting whoever compiles and uploads the binaries that they aren't doing anything nefarious.

One problem with app stores is the idea that they vet stuff. They may attempt to do so but that is just it. Its an attempt. You are trusting they did it and that the did a good job vetting. Apple and Google do this as well. Could happen on their platforms as well. For bitcoin, I would not trust any app store for apps touching any kind of real money. To much to risk for the convenience.