EXTREMELY UNEXPECTED HIGH PITCHED SOUND WHILE ON A CALL!!

I own an Apple iPhone 13, Just purchased last year. It's a great phone, except I've been having bug issues I've never experienced before with Apple. I've been an Apple user all of my life. Once you go with Apple is hard to change. I work on my phone a lot, so many times I need to merge calls to continue with the work call with more than one party. Six months after my Apple 13 phone purchase and also working on my phone happily and regularly, I started to not be able to merge calls. The phone just stopped merging. It wouldn't allow me to do my daily JOB (profession). So I went to the Apple store and in order to fix the problem they had to refurbish my phone and delete all my personal data (texts, emails, apps), literally EVERYTHING in order to get the BUG removed. The only thing is that after I left the Apple store I cried a river of tears, as I was not properly warned about loosing all my work emails and numbers. I spent over a month trying to recover all of that (lost unpaid time). Now...it will be one year that I purchased my phone last June and my hearing is at risk due to continuous extremely unexpected high pitched sounds, while on work duty (work calls). The sounds are so high that when I heard it the first time and had my ear buds on. I thought the sound made me deaf. I took my ear buds off so fast, just as you were being bit by a wasp and you want it out of your sight and closeness?!! It severely hurt my ear drums the first time, and the second and the third and so ON!! HELP!! And now I have to see an ear Dr. as the ringing sounds after these very uncomfortable iPhone experiences... WHY IS THIS HAPPENING?? Is it happening to anyone else? APPLE YOU NEED TO FIX TIS PROBLEM!! I've been a more than LOYAL Apple user. Any advice?