No one deserves to called a fake fan unless they're clearly bashing a member or an idol after claiming to stan/be a fan of them.
But have you ever been called a fake fan for a ridiculous reason?
For instance: called a fake fan for not streaming or buying merch/albums, called a fake fan for not liking a song, album, etc., called a fake fan for not knowing something about an idol, group, or a song, etc.?