Roku has ignored my bug report, but I wondered how prevalent the problem is that when using an updated Mac with Airplay 2 to extend the display to my newRoku Ultra (4800 series) with updated software, I find that frame rates are unbearably lower. Usually, I am using VLC to play media, but it doesn't matter if I am playing media, the rate is very low. The router is using Wifi 6, by the way.
Sound is decent, but the frame rate is ~10, if I had to guess - maybe less.
I have performed all the usual reinstalls and resets on both devices. Also, I find that I cannot use QuickTime player to Airplay to the device AT ALL, which is why I use VLC (which doesn't have an AirPlay button, hence the "extend display" usage.