Same for me, specifically started when I moved to Ventura. I've tried everything, including multiple rebuilds of Index.
It manifests as Spotlight not showing (or intermittently showing) in the search results list the icon for the file type association (Excel, Preview, etc). Most of the time there is no file type icon. If you option-click the entry in the list it (mostly but not always) makes the file icon the Finder icon, and correctly opens the Finder window where the file is.
If you click on the entry, Spotlight disappears but nothing happens. File does not open.
This happens for both files that are synched to OneDrive and those that are purely open.
It appears that Spotlight is not correctly reading file associations -- if I search for something and get a hit on an Outlook email, it generally (but not always) tries to open Apple Mail, which I do not use at all.
It's definitely a bug. It's definitely real. And it's definitely not a Dropbox/OneDrive issue as it affects all files.