Aqua Nautilus researchers have identified a security issue that arises from the interaction between Ubuntu’s command-not-found package and the snap package repository. While command-not-found serves as a convenient tool for suggesting installations for uninstalled commands, it can be inadvertently manipulated by attackers through the snap repository, leading to deceptive recommendations of malicious packages.
FWIW Flatpak also does it automated, but as others said they manually verify new entries, and since it’s such a widely adopted standard there’s less opportunity to name-squat a popular app that isn’t already available.
I don’t know what flatpak does to stop, say, someone releasing a legit/dummy app to pass manual verification before replacing it with a malicious app and a new name, so can’t comment on how effective their security is beyond the initial release