You aren’t wrong about the aur. Similar could be said about flat packs snaps Etc however. We should always audit our systems regularly.

That said, Manjaro is different enough that even enabling the Aur is a bad idea. I know from experience as I’ve done several reinstalls Etc. Because of Manjaro issues with the aur. They really shouldn’t even ship access to it. Because Manjaro does so many Breaking changes. It’s one of many bad decisions on the part of Manjaros maintainers. Ubuntu may be Debian and based. But it’s not Debian. Manjaro is the same.

The rest of them basically are Arch just with a few tweaks, themes, base install, and installer.