He is still active and people tend to be biased in some way to athletes that they have actually seen. For example, how many people have an opinion of John Havlicek? only the older fans probably. As for Kevin Durant on the other hand? Well everybody has an opinion about him. So recency bias plays a lot into it.
Lebron is more outspoken and political than Jordan. This means the crowd who just wants him to ‘shut up and dribble’ do not like his activist pursuits. And just being on social media and talking more in general means more to criticize. People scrutinize everything Lebron says and blows it up. Of course, when Bill Russell or Kareem was outspoken, people retrospectively praise them for that.
Lebron called himself the GOAT. Jordan didn’t. But hey, Wayne Gretzky was called the ‘Great One’, Muhammed Ali was called the GOAT etc.
Lebron is considered a ‘whiner’ ‘crybaby’ ‘quitter’ and the truth of this may be exaggerated. Lebron complains to refs a lot and flops a lot, but no more than any other modern NBA player. And the ‘quitting’ footage is either taken out of context or it’s taken from his recent seasons where Lebron has slacked off on defense due to his age and declining energy levels. Still, nobody has ever accused Jordan of slacking off on defense even into his older years.