It's absolutely true, look it up if you don't believe it.
So first thing I found was this time in 2018 where he found a video by a creator called E;R about death note, and reccomended him without doing a background check. So E;R was a racist and Felix didn't look further into it. When he was called out, he edited it out and publicly apologized. I don't think that makes him a Nazi, he just forgot to research what he was promoting. [1]
Now here's the second thing, which actually involves malicious intent:
Felix Kjellberg, who has 53 million subscribers to his “PewDiePie” YouTube channel, reacts as two men hold up a sign saying “Death to All Jews,” in a screenshot of a video he posted online. Mr. Kjellberg paid them to hold up the sign. The video was published Jan. 11 and pulled from YouTube this past weekend. The Indian men in the video apologized publicly in a video saying “we don’t really know what the message means.”
[2]
Now obviously paying people to say antisemitic comments is terrible, and I think Felix was trying to phrase this as some sort of """joke""" but I don't think this makes him a Nazi.
There hasn't been a history of behaviour resembling that of the ideals of Nazis from Felix, especially not enough to say that he partakes in those ideologies. Thankfully his "dark humour " phase ended years ago and he isn't doing these things anymore, so completely estranging him from anything for it is quite extreme, especially when I have seem some of this sentiment on Lemmy myself. Nor do I think he's a horrible person for edgy comments and actions that most of us have definitely done one way or another on the Internet.
[1 https://www.vox.com/2018/12/13/18136253/pewdiepie-vs-tseries-links-to-white-supremacist-alt-right-redpill
Good point