Ran into this yesterday playing the game for the first time. I use a non-qwerty keyboard layout (Workman) so I have to rebind keys in any game I play (I also prefer ESDF type layout to WASD and my keyboard is split with backspace on the left and space on the right, so I need to bind jump to backspace usually), and I primarily play my Deck docked, so this was rather nasty to run into right off the bat. The only thing I could think of was to undock the Deck and play handheld. I do often play games with a separate controller while docked, but when I saw in the controls that even the back grip buttons were used, I knew I didn't have any external controllers with enough inputs. Hopefully this can be fixed so I can get a better feel for the game. I didn't know about -nogamepadui also, so that's neat. I played like 2/3 of the tutorial sections but it was kinda hard to get into playing in such an unfamiliar way. I was pleasantly surprised to see gyro enabled by default as I've played a lot of Splatoon, but the way it works here with needing your thumb to be on the stick and only being on sometimes felt a bit weird, and it felt slow to turn around. Maybe just need to tweak my settings. Official Flick Stick support would be awesome. But I'm getting off-topic now...
What it says in the subject, in other Valve games that have similar functionality you usually can get rid of this by adding -nogamepadui to the launch parameters, in Deadlock this does remove Steam Deck glyphs but keyboard bindings do not show up.