Sometimes I am amazed at how dense I can be and still function.
Last evening my granddaughter advised me the hot water in the bathroom was slow, so I shut off the feed, removed the valve cartridge and gave it a clean and inspection. When I reassembled it, there was little change in flow rate, so I added new cartridges to my mental list. An hour or so later when I was brushing my teeth, I saw the cold water was also restricted. That's when the light bulb came on (very dim, mind you) and I took off the aerator and cleaned it.
Problem solved.
Memo to self: Keep it simple, Stupid.
Best
Les