as the person who pushed for the alpine core team (now TSC) to adopt a policy of rejecting telemetry features in alpine-packaged software, i have opinions on flathub 🙃
mostly i am concerned that pushing users to use vendor-provided builds distributed on flathub may be exposing users to harmful software misfeatures like telemetry in ways that they would not if those same users installed packages from a distribution which patches out these misfeatures as a matter of policy
i wish that flathub would explicitly ban telemetry and check for telemetry features during their review processes. i would be more likely to recommend flatpak in more cases if they did.