In a lot of important ways, Star Trek has always had high levels of fan engagement. From the '70s to the modern day, the world of Trek fan art, fan games, and fan movies absolutely exploded. Because of this, most people assume that Star Trek, as a corporate entity, is friendly to fan projects.
While that may have been true before, it is categorically untrue now. It all started with a crowdfunded movie called Axanar. Unlike most fan creations, Axanar was a professional-looking movie made by professionals who could afford it, after receiving over a million dollars in crowdfunding. Oh, and they sold a lot of Axanar merchandise that used homemade Trek logos, symbols, and settings. In 2015, Paramount unsurprisingly filed a copyright injunction against Axanar, but the film's producers countered by pointing out that Paramount never had actual rules of any kind for what fan projects can and can't do.
So Paramount called their bluff and created some. Now, fan films can't go longer than 15 minutes, and no stories can total more than 30 minutes. If there are any Star Trek uniforms or props, they must be "official merchandise" and not fan-made. Also, no professionals can help with making anything like a fan film. So Axanar had their belated rules, but these rules are so stringent, they threaten many long-running fan series, podcasts, and so on. Also, these rules conveniently force people to buy expensive "official" merchandise, just as salt in the wound. Trek was suddenly a lot less friendly to the fans who had kept it alive for decades, all because one fan-film flew too close to the Sun, and then challenged it to a fight.