I think that besides unverified packages, lack of repositories (for example, for FOSS only) is the main problem of Flatpak rn

Obsolete means it’s unmaintained (not true) and outdated because many packages get updates with noticable delay - it’s a tradeoff for being stable. Besides not seeing new Linux goodies on release day, some devs force you to add additional repos for their apps which can lead to broken dependencies in the future.

They are targets of American spyware.