Recent emojis are bald on iPhone 12

Yep. Normal.

Long answer:

Emoji are part of an international standard called Unicode, and are implemented across many platforms and devices.

The Emoji standard shifted some representations. You are seeing the results.

Here is the standard Emoji list, with suggested representations:

https://www.unicode.org/emoji/charts/full-emoji-list.html

Background on details including skin tones and hair, and the limitations of the permutations:

https://home.unicode.org/emoji/about-emoji/

Here are how many emojis were now becoming necessary based on the modifiers (look at the grids):

https://www.unicode.org/L2/L2019/19392-emoji-multi-recs.pdf