Some of those fan films are OK.
I was a Kickstarter backer for Renegades: Requiem. Then there was the big blow up with the other "fan" film producers that were behaving like professionals because they collected so much money, renting fancy offices and studios, paying themselves salaries, so CBS cracked down on all fan films. In response Renegades had to rewrite their movie to take out all star trek references, and rename the characters and organizations. They had already gone way beyond the new rules CBS put in place so there was no other option. It was going to be the final mission of admiral Chekov, but they just dropped his name and Koenig simply played "the admiral", the federation became the confederation, so it was pretty easy to imagine it was still Star Trek.