Follower not appear

Hello,
I click on the thumbs up (👍) for my chessclub friend "lichess_401"
it seems working but never appear on the list of followers when click on my profile whereas the others are fine.

is there something special on his profile ?

thank you

You're probably looking at the list of people who are following you, not people you are following.
To see who you are following, go to that same list, but click on '9 following' to see who you are following.