Timer alerts are late: alert is received from 3 to 5 minutes late when phone is locked and app is on background.

[fralacos]

Timer alert of the end of set time triggers from ~3 to ~5 minutes late when the phone is locked and app is running on the background. Tested on Redmi Note 10 pro and POCO F5 phones, both running MIUI 14 Global / Android 13.

Steps to reproduce the problem:

• Set a 10 minutes timer, start it, send the clock app to background, and lock the phone.
• Wait for it to trigger, while taking the time with another clock.
• 10 minutes passes, timer does not alert the end of the set time.
• ~13 to ~15 minutes passes, timer alerts end of set time.

With the phone unlocked and the application running in foreground, there's no delay.
With the phone unlocked and the application running in background, there's no delay.
With the phone locked and the application running in foreground, there's no delay.

Fail scenario was also tested with the clock app from google, with no issues: alert comes at 10 minutes mark as expected.

Simple-clock app is set to "No restrictions" on battery saving settings, has the "lock" to prevent memory cleaner to close it, and all notification settings were given, including the ones related to show on lock screen.

Using version 5.11.2 installed with F-Droid.