I had problem with blur effect not fading away after cooling. It only dissapeared after restart of the game. I figured out visual connection with opening HUDs while having reBlured mod installed. After removing reBlured, problem has been solved.

Fair, I should go and place a querry on their site as well then.
Thank you for response.

This might be an issue with ReBlurred. My guess is that when they apply their blur effect to the background, they don't re-apply the old effect properly when the menu closes. Shaders are tricky in Minecraft because you can only have one active at a time, so it makes juggling effects added by multiple mods very difficult.

I will be closing this issue, since I forgot this has actually been an issue for quite a while now. I will reopen the original issue if it is confirmed that Cold Sweat is at fault for this incompatibility.