Is it possible for iPhone's MAC or other network specifications to change through update to IOS 14?

Solution 1:

Yes, iOS 14 introduces a new type of MAC address randomization named "Private WiFi Addresses". This means that iOS selects a new, random MAC address for each WiFi network you connect to. Note that only the first time you connect a new address will be chosen - it stays the same for that network the following times you connect.

You can disable this behavior from the Settings app on the phone. Choose WiFi and then press the (i) button for the network in question. Ensure that "Private Address" is not enabled.