Three answers
Yes,
No and
Optional
The only in-line strainer I'm 100% sure of is the aerator and it's common to both hot and cold (The yes)
Most rigs that is the only filter (That's the no)
However the OPTIONAL is some rigs will have a water (Taste and odor) filter in the COLD water line at the sink to improve drinking water quality... Now the PROPER way to that is to add a 2nd faucet (Filtered water) but.... Not everyone does it that way epically if it's a DIY modification.
Other possible causes:
Depending on your local.. Frozen pipe
Debris in pipe (City water can have some interesting things in it)
Pinched "Pipe" or line
Cut off valve (I've not seen any in motor homes or trailers but who knows)
Failed valve
That last one is kind of high on the suspect list.
If weather allows. Fill fresh tank, turn OFF water pump and bleed pressure from line (Open any water valve) disconnect line under sink and using a plastic hose extend to either a bucket or sink, turn on pump and observer flow
If it's good, it's the faucet.. if there is a taste and odor filter.. that's where it's going to be so you will see it (it's usually a cylinder 2-4 inches in diamater with two pipes. either one on each side on the top or one on each end.
