This information about Haaland seems dubious to me. Firstly, I do not think that Haaland considers himself to be worse than Mbappe (and he has every reason for that, since Haaland reveals his potential much better than Mbappe). Secondly, even if Haaland is afraid of competition with Mbappe, how did the journalists find out about it? I'm sure Haaland will never say this out loud, even if it is true.
Can't recall the source honestly and whether it was an information coming from his friends or journalists but it sounded logic for me. It is like seeing CR7 joining Liverpool, he will play with Salah, Mane, Firmino. It doesn't mean they are better than him but there will be an intense competition, less goals, and your impact will be diluted with them. At the opposite, in La Liga there isn't much choice for the clubs. In Real Madrid for example you have VJ and Benzema, if you add Mbappe then it will be good, if you add Haaland it will be better for the club but not for the players.
I have no doubt that there is a source for this news, but it seems to me that these are just another inventions of journalists. And I know quite a bit about Haaland as a person, but it seems to me that it makes no sense to compare him with Ronaldo or Neymar, since I have not heard that Haaland would have such huge ambitions as these two and he would be very worried about having in team of other stars. In any case, we can only follow the news and wait. I think in a month the journalists will come up with a new story