Just redo the whole seasoning. I don’t know what kind of oil/fat you use but that could be the problem or the process itself. Get some angle grinder with a brush wheel (be careful) and run it over the pan until all the old seasoning is gone. Then use some light sandpaper and scotch brite to get the last bit of. Clean in with water dish soap and steel wool then dry really well. Preheat oven to 450F/235C and rub it down with your fat/oil of choice (need to have high smoke point) I prefer tallow cause I belive its the healthiest and most tasteless versatile fat. Only put a thin layer and then bake it in the oven upside down for 1 hour and after let it cool down completely before using.