Hi,
I had the same problem with my Iphone 7 plus, when I updated the new OS 12.1. I called the apple support and it said there was a hardware failure on the microphone. I said it was very weird when both microns stopped working when I updated their new OS. Because my mom works as a technician, she called in to support, who only asked her hard-to-reset phone and then reset to factory settings. What she thinks is strange when she was clear that the phone worked before the update and wanted it to troubleshoot before she started installing it. Which is the way to do when troubleshooting problems that occur during upgrades.
When it did not work she called back and only then did a diagnostic test on the phone. According to that, the hardware problem with the microphone that the diagnosis had discovered already when the upgrade was done according to apple, is always a diagnostic test at these upgrades.
The strange thing is that the Iphone 7 has 2 microphones and what's the odds that both of the 2 microphones stop functioning at the same time ???
A micronphone will record audio in movie recording and one manages audio during phone calls.
Mom said it was a strange way to troubleshoot the problem with upgrades but they claimed it would only solve the problem with the phone.
How are they able to solve it when it's not even the troubleshooted phone before I restore it to factory settings, how are they going to get it already if it's their OS that caused the hardware failure when all the data is gone ????
I have a case with Apple Support. You others who have the same problem should require them to create the cases as it is clear in this link that their OS created a hardware failure on the phones?
It's horrible that they have only 1 year warranty on hardware, it should take more responsibility for errors that occur in connection with their updates. This is extremely bad advertising for them !! They should take more responsibility as this is an expensive product and they definitely do not take their climate responsibility and develop sustainable and quality products. Because the products do not even manage their own updates !!!!