I am not going to upgrade from Catalina. My late 2013 12" MacBook Pro works fastest here; I've tried Big Sur, and I start to have beachballs, before I didn't. Not going to upgrade my OS, even if I upgrade to a 2017 MacBook Air (i7, 8 GB/128 GB). This is the sweet spot for me and my needs. Can't go earlier, because some of my software wants Catalina at a minimum. Can't go to M1, because I still need a Windows VM for occasional needs at work, when I'm on a remote call and I don't want to have to support another PC. I have Windows Update turned off on the VM, because I don't want the Windows 11 nag screens!
Catalina will stop getting security updates when the successor to Monterey is made public. I'm fine with that.