iPhone 13 Pro Max - Poor reception, distortion and bad call quality

I bought my iPhone 13 Pro Max around a month ago and have recently started experiencing issues with the call quality and reception. There is a lot of distortion in the calls as well but surprisingly this is all feedback by people at the other end of the call. Everything is perfect at my end and I can hear everything clearly. My signals are also always full and I never have any connectivity issues which I’ve seen other users complain about.

The interesting thing is that my network provider sent in a text message 2 days before I bought my new phone which stated that:

”Dear Customer, due to planned system upgrade, you may face temporary unavailability of few services on 2nd Nov 2021. Any inconvenience is regretted.” Please note that these issues at the network’s end continue to go unresolved till date.

Now my question is, is this related to my device or the network?