I also have a 2012 F150 with the 5.0V8. Had the water pump and thermostat replaced as the water pump was starting to leak, and when I got it back I also experienced the radiator fans kicking into high. My truck has never done this before so I knew something wasn’t right. I reached out to the mechanic and he verified that he did not use an OEM thermostat. I brought it back in and he replaced it with a motocraft thermostat and my truck is back to normal. Hope this helps someone else experiencing this issue after replacing their t-stat.