I would tend to believe the The Secret Gospel of Mark is authentic. Some of the details of it ties up the narrative.
I’ve been wondering why wasn’t Lazarus an apostle if Jesus really loved him. We have no problem accepting John as being “the disciple whom Jesus loved” and he was an apostle. Just looking at the Bible, it’s not clear why. The Secret Gospel of Mark makes it clear that Lazarus was a youth. So, the reason Lazarus was not an apostle was because he was too young. It could also explain why Lazarus was not mentioned in the other gospels. Yes, the other story of someone being raised from the dead was a young girl. But, it was included because her father was a ruler of the synagogue.
In the gospels, most of the time the word linen is used is in the context of a burial cloth. The only other times are the young man wearing a linen cloth and the story of the rich man and Lazarus. If the young man is Lazarus, then it ties up all the references of linen in the gospels to death and resurrection.