🔊 Oppo A78: Why is my phone speaker not working?

My Oppo A78 speaker suddenly stopped working properly, calls and videos now sound extremely muffled and quiet. Volume is already at maximum on the device. No liquid damage or physical drop happened recently that I am aware of. What could be causing the speaker to sound like this?

The issue could be caused by dust blocking the speaker grille, a software audio problem, or a failing speaker component. First, gently clean the speaker opening with a soft, dry brush and restart the phone. Check whether Bluetooth is accidentally connected to another device. Also install any pending software updates. If the sound remains muffled at maximum volume, the speaker itself may need professional inspection or replacement.