This is a resource pack that simply modifies the biome colormap (and for that, you need optifine/colormatic). This makes the swamp biome use its release 1.0 - 1.6 colors which were replaced in 1.7 with a fancy brownish-yellow gradient.

You may need to press F3 + T after loading the resource pack because for some reason colormaps don't apply properly the first time you load a resource pack (for me at least.)

This pack was made using this template: https://www.planetminecraft.com/texture-pack/default-1-16-optifine-grid-colormaps-for-resource-pack-developers/ Thank you so much!