I recently moved to a home with a well, previously only living in homes with
city water.

The previous owners had valves set to bypass the water filter. A few weeks
ago, I opened valves to divert the water back through the filter. In the
past week, the house water pressure has dropped significantly. If I close
the flow to the filter and reopen the valve to bypass the filter, the
pressure is fine. A couple weeks ago, I also drained and refilled my hot
tub, which required alot of water.

What's going on with sudden low pressure through the filter line? The
filter looks OK. Incoming and outgoing water is clear.

Also, my well tank had a preset pressure of 38 psi. There is a pressure
gauge between in the incoming house water and the tank that reads 50 psi.
Does this mean the air in the tank is 50 psi, and is this too high?