This only happens with resource packs using custom texture atlases in their resource pack. It also happens on singleplayer if you disable and re-enable a resource pack with texture atlases (F3+T does not work). I can reproduce since 22w46a.
As a quick note to @Magne, so they don't keep worrying, the launcher icon is white because you may be using the legacy launcher; it does not reflect your account status. Also, you're not at risk of losing your worlds. Since I'm also experiencing this without using the legacy launcher (which, to my knowledge, doesn't exist on macOS), this is likely a harmless bug on Mojang's end.
Caden Kriese
MC-249933
Still present for me on 2.2.7205 macOS, which seems to be the latest version I can get even with beta versions turned on.
I have also experienced this; I've added my crash log.
This only happens with resource packs using custom texture atlases in their resource pack. It also happens on singleplayer if you disable and re-enable a resource pack with texture atlases (F3+T does not work). I can reproduce since 22w46a.
I also have the white Creeper on macOS 13.4. However, I reinstalled the launcher and am back to the "legacy" less-vibrant grass block, as described in the icon update press release https://www.minecraft.net/en-us/article/our-icons-are-changing.
As a quick note to @Magne, so they don't keep worrying, the launcher icon is white because you may be using the legacy launcher; it does not reflect your account status. Also, you're not at risk of losing your worlds. Since I'm also experiencing this without using the legacy launcher (which, to my knowledge, doesn't exist on macOS), this is likely a harmless bug on Mojang's end.