Lyxen
Great Old One
There's a good example of what I meant. And, at the other end of 3e, you have Savage Tide Adventure Path, which the last third of the AP might as well be renamed Planescape Adventures.
Which, honestly, is great if you like Planescape and the Great Wheel, since there are very few adventures like this. Out of all the 5e modules publications, how many are really planar and based on the Great Wheel ? And how many supplements ?
Honestly, it's way worse for those who don't like the Forgotten Realms, since instead of the minority above, it's a large majority.
Look, I'll admit to just really not liking Planescape at all. I really, really don't. Which would be fine, except that Planescape is the basis for every planar monster, every module that deals with the planes, and everything else to do with the planes that gets released regardless of any other setting.
Oh, look, it's another demon type. Cool. Oh, look, a whole section on how it fits in the Blood War. Gee, that's great.![]()
Well, honestly again, this is mostly fluff, and apart from Eberron, there is no alternative planar setting, while there are many for adventures in general. And reskinning/refluffing is way easier for single entries than for complete adventures.
So I get that you don't like it, but it really does not seem all that bad compared to way worse situations in terms of adventures.