iPhone 7 Microphone not working after iOS 15.7.6 Update

My iPhone 7 (yes, I still have an iPhone 7) was working perfectly until immediately after I installed the 15.7.6 update. Since then, I can no longer pick up phone calls - the audio / speaker symbol is greyed out when I make calls or receive calls. The only way I can take a call is by using my AirPods. In addition, if I try to record a Voice Memo, nothing happens - I'm unable to record. After some online sleuthing I went ahead and reset all settings, and immediately afterwards the microphone functioned again, implying that the issue is software related, not hardware related. But the celebration ended quickly as the microphone stopped working again within a few hours....

Is anyone else facing this situation and is Apple taking a look at this? What can I do to solve the issue? Thank you in advance for your help!

[Re-Titled by Moderator]