I honestly don't think the mic issue will be solved by any software update because it is a hardware problem. I was told (and I see many people here saying the same) that iOS13 did something that affected the mic. In essence your (and my) mic was fried during that update. Once this happens, no software update can make it work again.
I was called on the phone by Apple Care in the US about 3 months ago because of this problem (probably because they get information from these discussions). They said they would replace my iPhone 7 by an equivalent one, but since I live in Europe I would be contacted by Apple in my country.
I was never contacted. I had to call them myself. Eventually they found the file, and told me they would replace my iPhone 7 by an SE 2020, to which I accepted.
A few days later someone else called me to tell me that I would have to send my phone first and they would send me the other one once they received mine. It was not what they had told me, but I accepted that as well. They promised to call me back to arrange the details.
Several days passed and nobody called me again, so I called them myself. They told me that everyone whom I talked to in previous conversations (from the US and here) was wrong, that this was not part of their policy. That I could send my phone for repairing but I would have to pay for that.
I was very disappointed, and decided to contact again the person from Apple Care in the US, but I was so tired by all this that I haven't done it and continued using earphones on the phone instead.
I should probably try and call them again or hope to be called again if they happen to read these threads.
