If the Litchi app requires a custom firmware install then it could very well adjust or control flight inputs. The DJI firmware is stand alone and does not require the app. The problem I see is software (the app) is notorious for crashing, resetting, or doing other strange stuff. In a bird where the app only affects the gimbal and camera the damage from an app crash is limited, but in a firmware enhanced app that crashed for whatever reason I can see disastrous results.