(though the guy alleging his video game was plagiarized was something he brought up before the dubious sources had(?): http://anas-tronaut.blogspot.com/2017/10/star-trek-discovery-tardigrades.html Which he may or may not have a case (I've not read much into it), though one or two issues are something of a stretch and it's not like Trek (especially TNG) hasn't showcased big creatures that exist in space before, but is it as overly simple as that? )
If I remember the timeline correctly (I was around when he first posted on reddit about it) he made that post and then every person who wanted to see the show cancelled glommed on to it (including the usual suspects on youtube), and pinned their hopes and dreams on this going anywhere and taking Discovery down. And there isn't really anything to it. Even back then I looked at his "evidence" and it was reaching pretty hard, and after actually actively looking into it, it pretty much evaporated into nothing.
We have a thread dedicated to that lawsuit in the Discovery subforum.
https://www.trekbbs.com/threads/its-going-to-court.296468/
Basically it's all a big coincidence.