It’s not a bug, just an unnecessary change and total laziness on the part of the TVOS team at Apple. They changed it to press and release for dictation, hold for Siri while not bothering to change the instructions to “press and release” from “hold to dictate search”.

It’s like this on all models now. Dictation is literally missing from both of mine, and only activates Siri. Totally axes one of the biggest Apple TV advantages. If it’s a bug Tim needs to fire some people because obviously they are not even testing these builds at all before just releasing them.