It's fruit fly season, again.
The flies are in some sort of bag or container in your fridge. If there is a bag of black liquid in there, chances are that's where they were bred. If you have an open can of veg or fruit they were bred in there. Take everything out of the fridge and you will find something disgusting in there. You'd be surprised what they can reproduce in. They are not only attracted to fruit but anything decomposing, like meat. Once you find the source, dispose of it outside in the garbage can.
Then use a dry paper towel to sweep out the dead bugs onto a paper plate or something else easily put into the trash and get them outside into the trash can because the cold might have put them in suspended animation and once warm they can swarm your home. Go disinfect your refrigerator with a solution of water and white vinegar (ratio of water to vinegar formula available online, somewhere) so your refrigerator has no toxic chemical in there and is clean and sweet-smelling but not the kind of sweet that attracts bugs. White vinegar is a perfectly effective and safe means of house cleaner. Obviously, your fly traps need to be IN the refrigerator back in a corner out of the way and out of your sight, not out on the counter as you don't see them outside the fridge.
Oh, and for your piece of mind, fruit and veg come already loaded with the little darlings; they don't just materialize out of nowhere and they don't migrate over the miles to you from the farms because you're dirty. The protein in fruit and vegetables is probably due to the fruit flies already being in the food waiting to be released once we take the fruit and veg home from the store. We most likely eat a certain amount of fruit fly larvae which is microscopic and allowed by the FDA.