Your NPub is showing only on your misskey profile. Not anywhere else. Not even on your GitHub profile.
Was that on purpose?
Discussion
Misskey profile is old.
I have nostter.app link in GitHub profile instead of npub.
Npub is hard to understand.
Ah!
Right!
My noster.app profile address shows my NPub.
https://nostter.app/npub1k8u5csaulf800zljf7tey95l6e42v38lxljcsu60rdpd7te3jpyqfgznyl