Even if the problem was only happening to people who upgraded to big sur (it's happening with everyone), this first version of a new OS has been beta tested for months. I'm pretty sure people can complain when an official version of a software is released...or really, whenever they want to. I complain all the time, and I love it.
Anyway, the general public is not supposed to be beta testing software, and even this site loves to mention how much and how quickly users adopt new versions of Apple's software. Maybe Apple should be waiting before releasing buggy software, but again, this is not just for big sur users. I imagine that this related to its release though.