Check the valve system first. Does the faucet give good flow? Do other faucets have good flow.
Is the shower hot amount to low.
A lot of showers have temperature balancers to keep scalding accidents down. You have to find or download instructions for your handle system. Mine you take off the cover and there is an adjustment screw to turn temp up or down.
Also, get under the cabinets or whatever near there. Could be a pinched pipe or creased going around a corner.
Last, could be a bit of construction junk, lime scale, etc. blocking the spray head, line or valves.
2017 SLX 195RB
2014 Jeep Grand Cherokee Overland, gas 3.7 V6
Andersen WDH hitch
Dometic Milenco Aero mirrors