Yes, that is the vent for your power converter. The DC side kicks on and off when any item is running, like RV refrigerators on DC, propane detectors, led lights on your entertainment system, the controls in your water heater, any light switches or electronics running on DC power that has led lights, anything like that.
If you flip on one overhead light, you'll hear it run louder. Flip on two lights and it increases as the fan runs harder, flip on everything, and it's putting out power to all your DC electronics, even louder In addition, it's also keeping your house battery charged.
Contrary to thought here, your DC system electronics do not actually receive power from the battery. They receive power from the converter, and if more power is needed (say, a slide out), the converter alone will not have enough "umph" to move the slides. It takes the extra "umph" from the battery to actually move them.
What you are hearing is perfectly normal.
2019 Montana High Country 375FL
2014 Chevy Silverado Duramax, 6.6L Dually