Clean the fans. If they are dirty they are out of balance, inefficient about moving air, and hard on their bearings. There is one fan under the machine and there might be another one inside, between the freezer and the frig. Really quiet machines use solid-state Peltier devices. They are slow to cool, cheap to run, but very expensive. You might have someone check the coolant; if it is low on coolant it is going to run longer to reach proper temperature. Note: In the interest of keeping your fingers unplug the machine before you fool with the fans.

Thanks a lot for your suggestions! I'd love to spend more, how would one find such a fridge with Peltier devices?

Have you tried cleaning the fridge coils/vents. Sometimes fridges can run louder when they are dirty.

Some independent review sites will also report on the decibel level of appliances. My suggestion would be to pick a few models in your price range and do some independent research on the search engine of your choice.

This anti-vibration pad reduced my refrigerator's noise by 1.5dB, though https://www.amazon.com/gp/product/B01B7ZH2LG

Thanks for the suggestion!