Do you want to rewrite your 'sources.list' file anyway? If you choose 'Yes' here it will update all 'focal' to 'jammy' entries. If you select 'No' the upgrade will cancel.
Checking for a new Ubuntu release There is no development version of an LTS available. To upgrade to the latest non-LTS development release set Prompt=normal in /etc/update-manager/release-upgrades.