2017 Silverado 5.3. Having similar issues here. Starter was sounding slow for a couple of weeks but it never failed to start. Figured I’d go for a new battery since I needed a new battery for my boat anyway and if that wasn’t the problem I’d just use my old truck battery in the boat. Changed the battery, started truck, worked perfectly. Turned it off to try a few restarts ........ click! Checked everything and noticed the starter wires and studs on the starter were looking a bit rusty so I took the starter off, disassembled and cleaned everything. The starter showed no signs of wear (brushes, bushings, reduction gears). Worked perfect. Starter was turning much faster and sounded normal again. Today I accidentally left the key on and noticed the warning about the battery saver feature was active. It started anyway........ once! Then back to the same “click” I was getting after the battery change. A charger on boost didn’t make any difference either. Gonna wait until tomorrow and check for voltage at the small wire while someone tries to crank it. If voltage there, I’ll check the feed from the solenoid to the starter. I’ll post my results.