big sur – Why does MacOS BigSur keep changing my network name?

I recently installed MacOS BigSur. I held off for almost a year, since I’m on a late-2013 MBP that was working just fine with Catalina, and I didn’t want to screw anything up.

Turns out, everything works perfectly, except that somehow, MacOS thinks there’s another machine with the same name in the network, and it started renaming itself in the Finder sidebar to machine(1), machine(2), etc. A few days later it’s now at machine (102). Nothing seems to be having a problem with this, but it’s annoying, and I’m afraid something will break eventually because of this.

Anybody have any idea what could be causing this, and how to fix it?