Cakes can also bake lopsided when placed too close to the back oven wall. The oven is usually hotter here and cake bakes faster where oven wall is hotter, not allowing the cake to rise as high. Bake a cake ONLY until it is done. OR it will be dry and tasteless. Box directions can only be guidelines.
Large eggs can be a factor, as opposed to small.
Remove it from the oven and cool for 10 minutes or longer. Either turn it out onto a cake rack or a doily or foiled cardboard. Cool thoroughly before icing. I can't get by without some guesswork here. I insert a toothpick or cake tester.