Why does SmartScreen still warn after I bought a signing certificate?

A valid signature and a good SmartScreen reputation are separate things. Signing helps show who published the file and whether it has changed, but a new app or publisher may still lack enough reputation for the warning to disappear. There does not seem to be a reliable timetable for building that reputation.

EV signing has been associated with faster reputation benefits, but I would not treat it as a guaranteed instant bypass. Check Microsoft's current guidance before paying extra, since the behavior and eligibility can change.

Make sure the release is signed correctly and timestamped, then keep the download and publisher information consistent. Reputation may depend on more than the certificate, including the particular file and possibly where it is hosted. Frequent rebuilds can mean the new file still gets flagged.

If you believe the file is clean, you can submit it to Microsoft's security analysis service and ask for a review. That may help identify a detection issue, but it is not a shortcut that guarantees reputation or immediate removal of the warning. Avoid asking people to disable SmartScreen as a workaround.

Also separate the browser's download warning from the warning shown when someone runs the app. The browser may consider the download source as well as the file, so stable hosting and a clear, consistent download page are worth checking alongside the signature.