I frequently find myself losing momentum at the end of things that I enjoy. For instance, I've been playing Baldur's Gate 3 and loving it. I recently got into the last act (Act 3) of the game, and I'm finding myself a bit burned out on it and gravitating towards other games. I'm also in the last episode of Dimension 20's Neverafter (yes, I'm a geek haha) and finding myself not interested in finishing it.
Does this happen to anyone else? I started on medication earlier this year, and lots of other symptoms of my ADHD have gone away, but this one seems to be persisting.
Tl;Dr you're not alone!
For me, like the article, once I'm at that point of the game I feel like I've seen everything to see.
That, and if I don't finish a game, there's still a little bit of mystery to uncover.