I've been doing a lot of reading online tonight about this whole ordeal. Someone mentioned CachyOS "makes it easy to install apps" or something in that vein as in it utilizes one click solutions for installing, so to speak. If these point to the AUR without checks and balances then yeah I could see that being quite a disaster.
I'm not sure I follow what you mean about better flatpak integration. Arch and flatpak play pretty nicely together as it is. It's just my experience that a lot of the more random and niche software I want is only available via the AUR and not flatpak.
Ultimately though, the AUR is the arch user repository. As in, it's maintained and contributed to by users, not the Arch Linux team that develops the distro. They provide plenty of warnings about using it at your own risk, and while it's certainly a big part of the appeal for the distro, it's no surprise that something that's basically the wild West will get a little unruly at times.