Shower valve making squealing/whistling sound when hot water is being used

[ttav9216]

I have a shower only and the shower valve would be making squealing/whistling sound when I turn the handle to hot (occurs after around 5 minutes of using). Not really sure what's going on. I have attached a video link to imgur for a better hearing of the sound. Could it be due to the cartridge being bad? I have a water softener and a tankless water heater at home. Everything in the house is less than two years old. Any help would be greatly appreciated!

https://imgur.com/a/pcj5QCm

 

[Jeff H Young]

Turn off water , remove cartridge, hold something in front of valve to direct water down or a bucket, Have helper turn on water have phone or be withen yelling distance, open water lettr rip , tur n water off thourghly inspect or clean cartridge , (or replace if you have an extra or an extra 50 bucks ) reinstall and test again lastly return with results to discus next steps