Why won’t my iPhone 14 Pro Max auto lock on games ?

when I’m playing a game in the night and fall asleep in the morning when I wake up I see my phone is still on and didn’t auto lock.

Auto Lock is set to 30 secs and has been tested on other apps. However this game - Last Fortress Underground stays on and drains my battery every day.

• Phone is up to date
• I have tested on other games and this is the only one that’s does this to me
• There is no additional settings in the game