Wastes RAM and disk space (compared to package-manager installed applications) by storing more libraries on disk and loading them into RAM rather than just using the libraries already installed on the distro. It’s probably better than Snap and Appimage though.
Is it even a problem for a desktop in 2024? Never had an issue with RAM or diskspace. And even for those that have, they can just not use flatpak until they upgrade, no reason to kill it.
What can flatpaks do that others -snap, appimage- can’t? At least they don’t have weird naming of program (com.sth.sth.fk)…