Sleep timer (sometimes) not working on Android 14

[Dstr8ction]

Overview

Since I updated my phone to Android 14, the sleep timer of Voice is not working reliably any more.
I mainly use it at night when I go to bed, to listen to my recent audiobook while I fall asleep.
My timer is set to 15min but in some of the past nights I woke up several minutes to hours later and my audiobook was still playing beside my bed.
Some other nights however it worked as expected.

Maybe it is important to note, that I turn on Airplane mode, Battery saving mode and DND during the night, but that was never a problem in the previous years that I used Voice as my audiobook player.

This never happened on Android 13 on the same phone.
Reverting to an earlier version of Voice didn't solve the issue.

How to reproduce

1. Turn on Airplane mode, Battery saving mode and DND.
2. Open the App.
3. Start playback of my recent audiobook.
4. Click on the button for activating the sleep timer (preset to 15min in my case).
5. Turn off the display of my phone and maybe adjust the volume if it is too high/low.
6. Hope for the playback to stop after 15min - most of the times it does not.

Version

8.1.2 and 8.1.3 (both installed from F-Droid)

Android Version

14

Device Model

Google Pixel 6

[azigit]

Same problem: playback continues after sleep timer reaches zero.
Voice version 8.1.3
Android 14
Pixel 7a

[Marqqss]

Can confirm that the issue is still there. Does not require airplane mode or anything like that. It is just rng that the timer works.

Voice version 8.2.4
Android 14
Galaxy S24 Ultra