I'm not sure if this can be called as bug but they seem like it.

There is a "bug" that allows you to fill things inside the onion skin. If you animate and you turn on the onion skin, and you use the fill tool, the onion skin will affect where you want to fill. Although this seems like a bug, it has a really good use for me when I'm animating pixels. I'm hoping no one will get rid of this bug, or at least give an option for this.

Another "bug" that I hope no one will get rid it is this. Make two keyframes frame. In Linux, you can easily duplicate a frame after the key frame by drawing on it. But in Windows, you can't. I like this "bug" because it doesn't make sense to me that it can automatically duplicate frames. Usually on other animating software, you don't do that.

Here's a video showing both of these "bugs" that I like.

https://youtu.be/jFMnitDyzWE