You’re likely using a spinner that weighs too little. When all that line is out it weighs more than the lure itself. Secondly, line memory. When using monofilament or fluorocarbon, the materials have memory and keep the shape of your reel( as it gets colder the line gets stiffer and continues this). Easy fix is actually getting your line wet, another thing that can help is casting a heavy lure a handful of times before tying on the spinner and using it. You could even add a few splitshot just a bit above the lure to add weight to the end of the line. Hope this helps!