I don't think the endgame content itself has anything to do with it. It's all fine.
For me personally, I lost all motivation to play the game after the MSQ. I don't think there's a lack of things to do, in fact the one thing Dawntrail seems to be doing well/better than Endwalker is battle content, and I don't doubt it's all great. A lot of the things we always expect to be there and the same are there and I probably wouldn't have anything to complain about - I've always had fun with those things every expansion. But for me the attachment to the game and the world came from the story and I haven't been interested or curious about it anymore. Sure I love leveling up my crafters and gatherers, but part of the motivation was to read the quests and the story and I'm just...eh. I don't know if other people feel the same.

I also dislike Tullyolal as a main city. Sure it looks beautiful, but it's too big and awkward to walk around and things are inconveniently placed and I don't feel like going there to do stuff. Again, usually the main story makes me attached to the places we've visited, and now I kinda don't feel anything about anywhere in Tural. Maps look pretty, and that's it.
I'm hoping when the new raid tier comes out I get back to feeling like playing the game again.