We've just released some fixes for SEO Checker on Umbraco V9 and V10. This is the last V9 release of SEOChecker. .NET 5 is no longer supported and an upgrade to Umbraco 10 (LTS version) is really easy.

Therefore, we decided to continue development on Umbraco V10 on all of our packages instead of building and testing on 2 versions of Umbraco.