In my fonts I have: EmojiOne Color, Noto Color Emoji, and Segoe UI Emoji. Comparing the emoji in question, this is Segoe UI’s grimace emoji. The kissy face emoji also works here. I also cannot replicate your problem on my Mac (12.3.1).
but I tried five themes and default theme, and they are all have this problem (colorless in edit mode and colorful in reading mode ) . Maybe some settings can edit heading color appear?
and I found a more abnormal thing like follow :
for comparison purposes , I using source mode
if using one-level heading , appear : colorless
if using two-level heading , appear : colorless
but using three-level heading ,appear : colorful ???
so it maybe not font’s problem