Master shower heads clogged with limescale build up. Customer already had ordered two replacements and they’re already on the way. Master shower both shower heads have low pressure. All other shower heads upstairs same floor having no pressure issues. Removed both shower heads and verified water pressure was fine. Replacing the shower head reintroduced the issue. Removed flow restrictor for time being until customer gets new shower heads in the mail. Water pressure tested at 75-80 psi. Not a PRV issue.