My "new" model remote with a Siri button keeps needing to be reset to control my infrared amplifier. Press and hold the Volume Down and TV button works, but it's annoying when you want to change the volume whilst watching something and it doesn't respond.
The firmware on the remote was supposed to update after updating the AppleTV. I guess the update didn’t fix it. Pressing TV and volume down for a few seconds restarts the remote which usually fixes it for a while.
I’ve noticed this happens when I click volume up or down repeatedly a lot of times in rapid succession instead of just holding the button down. It hasn’t happened to me since I’ve tried to be conscientious about it, but ymmv.