Theoretically, you could change the /etc/apt/sources.list/gitlab_ce-gitlab-ce.list file entries from jammy to focal, and use the standard apt install commands as per the Gitlab docs to continue your upgrade.
Theoretically, you could change the /etc/apt/sources.list/gitlab_ce-gitlab-ce.list file entries from jammy to focal, and use the standard apt install commands as per the Gitlab docs to continue your upgrade.