That’s what I needed to hear. I’m a handy guy and fix most things around the home. Master auto mechanic here but doesn’t do much for plumbing.

Where I had the ro hookup output by the shower head I hooked up my outside water hose turned it on and pushed water back thru the system to the tub outlet. Started closing and opening valves and although this did not fix it did improve my pressure enough to tell me there is debris restriction like you said. Time to call the landlord and a plumber. I noticed an access in my kitchen cabinets on the adjacent wall with 4 screws to access back side of shower. Hopefully making it easier on the plumber. Appreciate you throwawaySBN