The native Clock app only plays sound through the Earpiece instead of the main Speakers on iOS.

After updating to iOS 16.7.11 (20H360) released on April 2025, the Clock app outputs the sound for the Timer only through the Earpiece instead of the main-speakers. The only compromising way to temporarily bypass this is going to Settings > Face ID & Passcode and turn off "Attention Aware Features" option but isn't a permanent fix.

The device has already gone through a manual restart, restore if not reboot from a software update itself where Face ID too was setup from fresh to leave for any usual troubleshooting recommendations. Reinstalling the Clock app itself was done as well which didn't reset the sudden appearance of this surprise bug out of nowhere.

My most typical use case is to set a timer for an hour or two while playing Call of Duty®: Mobile game on Cellular+WiFi with bluetooth earbuds (JLab GO Air Sport) as the device is plugged in to a charger and also attend calls mid-session for replication.