I cant say actually. I have two apple tv 4k second gen and both connected each directly to an LG cx oled which feeds passthrough audio via earc to a receiver and a sound bar. One is running 15.6.1 and the other the latest 16.0. Neither in this connection configuration show a problem. Both are connected via ethernet. If i have time i will connect the apple tv running 16 to the receiver and try that. When i tried previously hooked to the receiver directly running 16, it was perfect.
On edit: hours running through my receiver and had no hiccups with netflix DV/atmos stuff running the latest version of 16.