Weird sound issues on iPhone 14

Hi guys,

yesterday, I got an iPhone 14 from a friend of mine.

He complained the iPhone doesn't play any sound.

What I observed:
The iPhone does not ring on incoming calls, doesn't play music or any kind of media sound and no system sounds.

When changing ringer volume manually in settings, there's sound! But it sounds a bit crooked.

What have I done so far?
I swapped both lower and upper speaker with new genuine parts - problem persists :/

Is the audio ic probably bad? This would make the phone ready for trash...

Maybe someone else already faced the same or a similar issue...

Thanks in advance!