How to stop screen of iPhone 12 mini going to sleep for certain apps

I have an app on my iPhone 12 mini that tracks my cycling activities call Livall. When I cycle on my bike using the app the screen used to stay on for the total duration of my cycle route. However, recently the screen goes to sleep after the set time if I minute. What have I done and can I restore this function? When I initially set up the app I did not set anything with regards to screen time, it set it up not to go to sleep automatically by the app.