Engine noise under load

I noticed while pulling my 16ft trailer with my side by side trailer that if the truck downshifts to 4th and revs up there is a higher pitched whining noise from the engine area. Only happens when the truck is warmed up. It’s happened the past two times I’ve towed my trailer. It used to not make this noise. I’m not sure if it’s RPM related or trans related. Any ideas?

Truck has 41k miles on it. I run 5w-30 oil for towing and living in the hot south. My trans temps are around 230 constant towing this trailer. My truck is a ‘20 with no cooler. Other than the whine, the truck drives and shifts perfectly. I have not tested it unloaded yet as I normally paw paw the truck around. Thanks!

 

Could it be pinging/detonation? Check out videos on YouTube if you’re not familiar with the sound.