Dyeable items - namely leather armor and leather horse armor - render as white regardless of dyed color when ray tracing is enabled. When ray tracing is disabled, the items render as expected.
This only affects items - blocks such as wool and stained glass which can be dyed are not affected either in item form nor in the hand.
In case my PC specs are important, they are as follows:
CPU: AMD Ryzen 7 3700x
GPU: Nvidia Geforce RTX 3080 (Alienware OEM)
RAM: 16GB DDR4
OS: Windows 10 Home (listed in its own field but to be complete)
Can confirm this happens as well.