I used Arch for a decade before Manjaro, and I was under no misapprehension that the AUR was anything except a collection of community package builds of wildly disparate maintenance levels, with some very popular packages waiting weeks or months for updates.
If anything, the AUR got more stable in my experience when I moved to Manjaro. If you're thinking there is any quality control and/or support keeping anything in there consistent, then you're a bloody fool.