Timer not working if auto-lock is same as timer. Fix this already Apple!

If I set a timer on my iPhone for the same time interval as my "Auto-Lock" Display setting, and then I don't touch the phone during that period, the timer will not sound, or the sound will be cut off almost immediately. For example, I have Auto-Lock set to 5 minutes. If I set a timer for 5 minutes and leave the phone alone for that time, the timer expires without the phone making any sound at all. A timer set for 4 or 6 minutes works correctly. This has happened since I’ve had the phone. How can I fix this? This is on an iPhone 13 with iOS 16.3.1.