Maximized window seems to bug out Character Controller movement in Unity 2020.1.12f1

I just upgraded to Unity 2020.1.12f1 and now my Character Controller "bugs out" when I press Maximize or Maximize on play. My previous version was Unity 2019.1.10f1 where this works fine.

Notice how slowly it starts to move once maximized, it also seems to do some random stutters? Sorry for the bad quality but the problem should be rather obvious.

Making the code run in FixedUpdate instead of Update seems to have solved this problem. Not sure why this worked in the previous version.