While there is many things wrong with gestures for years now, I'm going to mention this one because it has personally bugged me for ages.
When swiping home to an app within a folder, when the folder reaches its position it then changes colour, I assume to correct with the wallpaper. This shouldn't be a visible change, it should always be the correct colour. I have tried to attach a video, but who knows if it actually works. Additionally, the notification indicator bubble at the top right also pops up jarringly with no animation. These little things add up and can really make a difference on how the software feels.
Also when are we fixing gestures for third party launchers?