Recently this "app" has shown up on my phone. Tapping it gives me access to things like the home and back button, as well as screen lock.
I can't figure out what app or setting has caused this to show up recently and I'd very much like to get rid of it as it gets in the way of using other applications. There aren't any apps that I see in the settings panel that I recognize as being this kind of tool (Lux, Twilight, Lumen, "toolbar", etc).
Thanks for adding the comment. This looks like the "Navigation Dock" feature of Huawei's EMUI. Because these Chinese system skins will include all features that are included with an iPhone.
You will find the option to disable if you search for navigation dock in your settings app.
It should also be somewhere here (varies slightly per device).
Settings > Smart Assistance > System navigation > Navigation Dock.
Let's see how that goes.
Q & A