What is the trigger for JFrog Artifactory to sort a nuget package as "prerelease"?

Question

I got a compiled dll file (no source code) and built a nuget package out of it, so it can be distributed within our company. If I copy the nuget package to my local nuget package store, it shows as normal release. If i deploy it to JFrog Artifactory, the same nuget package is considered as prerelease and is only shown in Visual Stuido nuget package manager if i tick the 'Inlucde Prerelease' checkbox.

What is the trigger/condition for JFrog to mark the nuget package as Pre-release? I used the semantic versioning (MAJOR.MINOR.PATCH) for the nuget package, but the built dll is using the Assembly Versioning (Major.Minor.Build.Revision).

nuspec file:

<?xml version="1.0"?>
<package>
  <metadata>
    <id>MyPackage</id>
    <version>1.0.1</version>
    <authors>Author</authors>
    <owners>Department</owners>
    <requireLicenseAcceptance>false</requireLicenseAcceptance>
    <description>description</description>
    <summary>description</summary>
    <copyright>Company</copyright>
    <language>en-US</language>
  </metadata>
  <files>
    <!-- Include DLL files for .NET Framework 4.8 -->
    <file src="MyDll.dll" target="lib\net48" />
    <!-- Include PDB files for .NET Framework 4.8 -->
    <file src="MyDll.pdb" target="lib\net48" />
  </files>
</package>

Edit: I found out that JFrog is sort of corrumping my nuget package. When I download it with VS, it doesn't work. When I copy the exact same source nuget package to my local nuget package source, it works.