If the Trash contains folders of recovered files
One or more Recovered Files folders may appear in your Trash after you restart your Mac.
The recovered files are temporary files used by macOS apps. Usually temporary files are deleted by an app when it no longer needs them. If an app quits unexpectedly, it may not be able to delete the temporary files before it quits. When you restart your Mac, macOS moves these temporary files to the Trash.
You can retrieve useful files by dragging them out of the Trash. In most cases, however, the temporary files are not important and it is safe to empty your Trash. Check with the developer of the app if you’re not sure.