This is what I would do, assuming you do have access to the cloud provider control panel. If you don’t have that then I would suggest asking for it.
- use @pfaffman 's recommended method Move a Discourse site to another VPS with rsync but to a different, temporary, server, with a temporary host name. Yes, you will have the host name problem but you can test if everything is ok
- take a snapshot for safety and then reinstall your current server from scratch on Ubuntu 24.04 LTS. Most cloud providers will allow you to do that while keeping your IP address
- use the recommended method again to sync from the temporary server to the newly installed server with the existing IP address
- when everything works remove the snapshot and temporary server