I too joined in 2018. I have seen the old maps tbh, but having never played on them originally I just feel lost and out of place in the same way those who played on the original maps feel lost and out of place on the new maps. It is like the same sort of feeling when you first join a game and know nothing about it.
Exactly ^ I myself, while I do dearly love the old maps, I hated the new ones because A; I didn't know how to get anywhere, and B; everything was unfamiliar and new. After some time though after I took a moment to run around the new maps, I learned the layout just like I did with the old maps. That really helped me to appreciate the new maps more and see all the work put into them.
In all honesty, while I do love the old maps for various reasons, if you take a step back and look at them, they're actually very empty and bland. Most of those maps were actually unfinished by the time FeralHeart released I believe, hence them being empty. South Pole for example... it had, like, one meshs in it plus two portals. That was it xD Last cave on the other hand, it had zero meshes. Nothing. Nada. Zilch. On top of that the larger maps such as Fluorite put strain on the server, hence why it would have a habit of crashing. A change had to be made, and again while I don't agree with how it was handled, the maps are still very good.