It sounds like you can submit a request for a correction from Microsoft. Unfortunately, that seems like the only way.
You can see how to do that here: https://fb.smartscreen.microsoft.com/smartscreenfaq.aspx#question-11
“You can immediately submit a request for a correction. Microsoft Defender SmartScreen has a built-in, web-based feedback system in place to help customers and website owners report any potential false warnings as quickly as possible. In Windows Internet Explorer, from a red warning, click More information then Report that this site contains no threats. This will take you to a feedback page where you can indicate you are a site owner or representative. Follow the instructions and provide the information on this site to submit a site for review.
To report feedback from the Internet Explorer Download Manager, Right-click on the blocked download and choose Report that this file is safe. This will take you to the feedback page.
Once a dispute is submitted, a team of graders inspects the site in question. All disputes should be submitted through the website reporting process to ensure the quickest resolution.
In Microsoft Edge, click More information then Report that this site does not contain threats. “