Problem Oneplus 7 pro microphone problem



For several months, the people I talk to on the phone can't hear me very well (it's almost impossible to carry on a conversation).
A few months ago I dropped it in the water for a few seconds. I honestly don't know if it's related or if it's a coincidence, I don't remember if from that day I started having problems.
I mention that when I change the speaker (or headphones) everything is ok.

Is there anything I can do? Maybe a factory reset would help. Or do I have to send it for warranty?