Please help us help you and fill where relevant:
LimeSurvey version:  LimeSurvey Community Edition   Version 6.0.7+230515 
Own server or LimeSurvey Cloud: Own Server
Survey theme/template: Sea Green (Default admin theme)
==================Dear Experts,We are currently running an older version of LimeSurvey on Ubuntu 20.04, and we need to migrate the survey data to a new VM running Debian 12, where we plan to install the latest version of LimeSurvey (this VM also hosts Grafana).We only have one active survey, which is used to collect feedback after IT tickets are closed.Would you kindly advise on the proper steps to perform this migration? I'm not very experienced with Linux, so any detailed, step-by-step guidance would be greatly appreciated. 

The migration of the the server can not be handled here, only Limesurvey related things.

To move Limesurvey to the new server you can have different approaches.

1. Make a copy of the Limesurvey database, import it on the new server into your database server and have a new install using this "old" database.

2. As you only have 1 survey, you might want to install a new instance of Limesurvey on the new server and export the one survey as LSA (which includes the survey structure and the collected data). If you do not need the previous responses, just copy the LSS file and start from scratch.

However, option 2 will require that you setup users etc completely new, so if you have a lot of users, you might want to go with option 1.