The AUR, Snaps and Flatpak are optional, they are not enabled by default, the user may enable them at their own risk.
DDOSing the AUR was a ONE TIME ONLY thing, due to a bug, it was fixed quickly. This rubbish keeps on getting trotted out as a reason not to use Manjaro… do the Devs of other Distros NEVER make mistakes? Not in my experience.
I have not seen any Proprietary software offered, or installed by default, and I have installed Manjaro on Multiple computers, and there was certainly no proprietary software when I tested Manjaro in the VM.
Fortunately I don’t bother with the SO CALLED experts that blog on youtube, so I was never influenced by any of this rubbish (I would prefer stronger language where these idiots are concerned, but well, filters, shrug)
ALL of my Manjaro install on different hardware have been stable through every upgrade.
In my time as a Linux User since 2000 Manjaro is the best Distro I’ve used (and there have been a lot) since Mandrake KDE, which had user oriented functionality Ubuntu dreamed of when Ubuntu was released.