Reduced water flow from pump

On some (if not all) there is also a strainer in teh tank attached to the outlet. Mine had two of 'em ONe was hooked up in front of the actual output line to the pump.. the other was a 2nd port that was plugged (it is now a drain port).

Just so you know. I do not know how common the outlet strainer is. But if it gets "Slimed" up you will get what you got.

2nd: The water heater also acts a bit like an accumulator (pressure tank) and if the pump is simply not up to demands.. Same effect.

Blow air backwards from the faucets towards the tank and see if anything comes out.

You could blow air through the tank supply line to the pump to see if that clears it

It does have a filter, like itinerant1 showed above, and it was clear. Here’s what I suspect.

I cut a 1.5 inch hole in the top of the water tank last year b4 storage. Why? The ribbed water fill line (not city water) had a big valley between sidewall and tank, preventing any water passage not pressurized like from a hose. I could get tubing on a hose-end past the dip and force water in if available, but there would have been no way to reasonably fill the tank on the rare occasions of just pouring it in, like prolonged dry camping maybe. And the inlet to the tank was down on the side of the tank with limited space, so pouring would have been a challenge.

So, the hole on top. The tank’s under a fold-up bed, so easy access to its top. I put a food grade stopper tightly in the hole. Anyhow, I suspect some plastic shavings fell down and made their way into the water line enough to restrict the flow. The round piece from the drilling I got out. So I may be looking at purging things somehow.

Hope that all makes sense.

If your pump doesn't have a filter, it may have sucked in some debris that's preventing if from working up to it's capability.

It fix it, you could take the pump apart and clean or replace the diaphragm

Have you tested if it is only with the pump or does it have the same problem on shore water? If both then clean faucet strainers. If only pump then remove and clean pump filter.

Is there a small screw off filter/ screen before the pump? Possibly filled with debris.