Anyone else have water pressure that drops randomly when someone flushes or turns on another tap?

That’s mostly your pressure balance going off. What happens is that older homes use shared lines that can’t keep up with multiple fixtures at once. If it’s happening all the time, your pressure regulator could be out of tune or the main line partially clogged with mineral buildup. Happens a lot in places with hard water. Replacing a pressure regulator or cleaning a corroded line can bring things back to normal. Also worth check your shut-off valves — if they’re not fully open, that alone can cut pressure. We’ve seen people replace faucets for no reason when it was just a half-closed valve the whole time.