Install Zabbix 6.0 packages from official repo. This installs an additional preferences file so apt chooses 6.0 instead of 7.0 that is available from upstream repos:

cat /etc/apt/preferences.d/zabbix
Package: zabbix-*
Pin: version 1:6.0.*
Pin-Priority: 1000

But after upgrade to 7.0 release this file remains and already installed packages are locked to version 6.0.

Expected: After upgrade to 7.0 release the file should be removed.