Yes, definitely not foolproof. This is more of a wake up call to be at least careful and reconsider every single AUR package one has installed. For me, I was lucky too. But in my case it wasn't pure luck that the few AUR packages I have installed aren't affected. See, because since years using the AUR (sparingly! including my own package :D ) I always feared off orphaned packages and removed them as soon as I could. This incident here is proof I was right.

For some stuff I also prefer the Flatpak, because I do not trust everyone on the AUR, as they operate on root rights! When I brought this up on Endeavor, they disliked my opinion (as a fresh user) and the trusted community members there explained to me that the AUR is way more safe than Flatpak, because there is a trust system of upvotes and everyone can flag the packages, and that Flatpak has a wrong sense of security. That is what they told me and totally ignored my issues with AUR... one of the reasons why I do not visit the EndeavourOS community... I digress...