We have a brand new moen posi temp valve and new cartridge along with new plumbing installed. When turning on the water, as you get hotter the water pressure gets lower. Only seems to be when you get to all hot water (not mixed with cold) We’ve replaced the 1222 moen cartridge and it still does it. Not sure if this is part of the posi temp design or an issue with the valve. All other faucets in the house are fine.