I have the exact same issue. Macbook Pro latest gen, Alfred 5.0.3, Ventura 13.0 just installed, new Dropbox 159.4.5870, I added Dropbox to the search scope but Alfred can't see any files stored in Dropbpx. Not using the version where files disappear online. All these files were being routinely found before. Spotlight finds the files with no issue. Alfred diagnostics sees no issue.
Seems you need to check this for yourself with latest Dropbpx, and fix this behavior asap. Many thanks.