I got a Mac Mini several years ago that came with Catalina. I hated the new look of Big Sur, so I never installed that. I now want to install a newer MacOS (Monterey), but initially and perhaps ...
Stop dual-booting to test other OSes. There are faster, safer ways that don't risk your data or slow down your workflow.
Partitioning your hard drive is part of the process and could affect your current data. Make sure to back up your system completely before you begin. Depending on the arrangement, you may need to ...