upgrading project from 2020 to 2035

I was using 2020 and autodesk just stopped it.  I upgraded to Revit 2025, thinking that these types of software with their upgrades, will upgrade a project to a current version.  When I looked for previous projects in 2020, Revit 2035 didn’t see any.  Since 2025 is new, and I’m new to it, is there a function that I’m missing?   or Revit 2025 just doesn’t upgrade previous versions?