Hi there, @Michael3. Welcome to the Community.
While your phone itself may support 5G, it's important to keep in mind that your monthly plan also needs to be 5G enabled for you to make use of the speeds. When you upgraded your phone on a new contract, you would've needed to change your plan as well, hence the change in 5G access.
When you look at your plan details in MyBell, does it say "5G Access", or "No 5G Speed"? If the latter, you do not have a 5G plan and would need to change to have access to 5G again.
Looking forward to hearing back from you.
