Several files moved between ports in texlive 2020. To prevent you from encountering activation errors when upgrading to this version, Dan programmed the ports to automatically deactivate conflicting ports during the upgrade. This is our normal strategy in such situations.
sudo port upgrade outdated should have left you with a complete set of updated ports, if everything updated successfully. However if any port failed to upgrade and you had to intervene to fix something, one of the outdated ports might already have been deactivated but its replacement might not yet have been installed. MacPorts doesn't consider inactive ports to be included in the set of outdated ports, so a subsequent repeat of sudo port upgrade outdated would not have upgraded the previously-deactivated port and if you wanted to continue to use it you would have to upgrade it specifically, as you did.
