There’s also some issues with the 122 kernel, i had been using the 121 kernel until this update and running cat /sys/class/amhdmitx/amhdmitx0/config gives the following depending on the content:-
+-----------+----------+------------+------------+
| | | 121 Kernel | 122 Kernel |
+-----------+----------+------------+------------+
| GUI | EOTF | SDR | SDR |
+-----------+----------+------------+------------+
| | Depth | 8bit | 10bit |
+-----------+----------+------------+------------+
| | CS | YUV444 | YUV444 |
+-----------+----------+------------+------------+
| SDR Video | EOTF | SDR | SDR |
+-----------+----------+------------+------------+
| | Depth | 8bit | 10bit |
+-----------+----------+------------+------------+
| | CS | YUV444 | YUV444 |
+-----------+----------+------------+------------+
| HDR Video | EOTF | HDR10 | HDR10 |
+-----------+----------+------------+------------+
| | Depth | 10bit | 10bit |
+-----------+----------+------------+------------+
| | CS | YUV422 | YUV444 |
+-----------+----------+------------+------------+
Notice that the 122 kernel outputs 10bit regardless of content and HDR10 uses the 444 colour space instead of 422.