Questions about home water pressure (105-110 PSI range) and the drastic pressure drop when a single faucet is opened

I live in a three-storey townhouse and have measured with a pressure gauge on an outside faucet, at the laundry machine cold water feed and on the hot water's hose-compatible drain a pressure of around 105-110 PSI. For additional context, there is a pressure reducing valve installed just after the incoming main that looks to have been put in when the house was built. When I open a faucet or flush a toilet, the pressure appears to drop to mid-20 to mid-30s PSI. Is this normal?

The reason I started looking into this is because the pressure drop is super noticeable when taking a shower and, at least until recently, I had never noticed issues when a toilet was flushed or even a dishwasher or laundry run when I was in the shower.