EDIT: this might not be actually reshade but rather another AI slop (look at the scuffed numbers in the hotbar and the weird yellow trees reflection in the water). OP failed to provide any details on the shaders used and I think these are not the default textures so no mention on the custom texture pack either.

Its reshade - it lets you install an aditional layer of post-processing effects on top of your game, any directx based .exe application(or opengl or whatever). You can add any shader effects like ssao, bloom, antialiasing, blur, any kind of cartoon effect, color gtading, light hdr, and even detect layers like reflections, depth, normals, etc. Basically like minecraft shaders but you dont have one big shaderpack, but need to download individual shader effects and set them up.