I have questions essentially about deregistering iPhones and separating my cell phone numbers

I have an iPhone 11 Pro Max through Verizon and I have a second iPhone XS Max through T-mobile. they both have separate telephone numbers. I broke my iPhone 11 and recently received a replacement for it through my insurance provider. When I set up the phone and put in the new Verizon Wireless SIM card that was sent with the phone, the phone was automatically connected to my T-mobile phone -- the notifications would go to both phones, all of the settings were the same etc.

in the past, I was able to login into my iCloud account from both phones and I would still be able to receive messages to iPhone 11 number and the iPhone XS number; but now it is not allowing me to use my original Verizon phone number on the new phone that I just set up.

Would I need to reset the replacement phone and try restoring it from a previous phone backup in iTunes (from the iPhone 11) or do I need to contact my phone carrier?