Volume shortcut keys don't always work

I have a Mac mini and a MacBook Air, both of which exhibit this problem, which makes me think this is an operating system bug rather than specific to my device. I don't remember ever noticing this before upgrading to Big Sur almost a year ago, and the problem still hasn't been fixed even after several release patches over the months.

When I press the volume mute key to toggle muting/unmuting the system sound, the sound icon in the menu bar does not always reflect the current volume state. Sometimes it does, sometimes it doesn't. The popup (which appears toward the bottom-center of the screen and fades away after a second) always reflects the volume change, but the icon in the menu bar does not.

The volume setting does not actually bug out - in other words, even if the system icon doesn't update correctly, the actual toggle does perform correctly (if it was previously muted, it's now unmuted, and vice versa). So this just seems to be a UI glitch.

Anyone else experiencing this/is Apple aware? To try and reproduce: just hit the mute key on your keyboard several times in succession and pay attention to the volume icon in the menu bar.

I have reset the SMC, PRAM, etc., and even reinstalled the OS (for other reasons), none of which actually fixed it (plus this happens on another, newer Mac too), hence why I think this is a bug in the OS.