In my seed there are three Mistlands biomes that I visited before the update. All three still look the same with the spooky trees and spider webs and giant skulls. But now there are seekers, seeker soldiers, gjalls, rabbits, and Dvergr there. I like it because it adds variety to my world with these three quasi-Mistlands biomes, and it's creepy seeing the gjalls floating through the haunted forest and the seekers buzzing around. I saw someone on Twitch with a pre-update Mistlands that looks like yours. It's pretty desolate without the rocky textures added to the hills and without the trees.