By default, a squeezed 4:3 render gets a visibly narrower field of view than native 16:9 — r_aspectratio in gameinfo.gi overrides that. Browse different perspectives, or select two for A/B testing.
edit gameinfo.gi found in steamapps\common\Deadlock\game
} ConVars "r_aspectratio" "2.40"
wanna go back to normal fov? just delete the line you added.
make sure to uncheck Custom resolution in Deadlock's display settings