But maybe a more direct method of diagnosing flow. Pull the valve body apart on the offending faucets and make sure they are not clogged/blocked. Additionally you could remove the plastic line from the faucet and flow it into a container or longer hose routed outside. Lastly, kinked lines? They don't seem to have any standards when it comes to installation. If the water lines are bent to sharp, they can kink and restrict flow. Hot water lines are more susceptible since they get easier to bend as they warm up.
I agree with the outdoor shower situation. If you have a hose shutoff (in the off position) and both hot and cold water valves in the on position, you could experience some back-flow between hot and cold water lines.
Good Luck, curious to know what/how you finally resolve it!
2013 Voltage 3905 Black Full Paint Finish
2001 Dodge Ram 3500 Sport, 5.9 Banks Turbo and Ottomind, Jacobs Exhaust Brake, Airbags, 6 speed manual trans. 2015 Polaris RZR Desert Edition in the garage.