A dot appeared on the screen of Huawei p10 lite. What to do?

Question

Android

Hello everyone, just the other day I got a white, semi-transparent dot with a grayish and translucent outline. This button performs the function of going back 1 step. It can be moved, but by holding it a little, its center moves in the same direction, where you move your finger across the screen. I've looked in the settings and can't find anything. I hope you can help, because she's been annoying me for a couple of days now. Thank you for your attention!