I'm running into a strange issue where the wrong domain is sometimes set in the rel canonical tag. I'm pretty sure the problem is that Document.ContextInfo.Host is not returning the expected domain for some reason. When I call Model.Url(Culture, UrlMode.Absolute), the correct url is returned, so this appears to be an seo checker issue.

Fortunately, it's not difficult to work around with a find and replace, but ideally I wouldn't have to take that step. I also updated the package to 2.11.5, but I'm not sure that will help as the changes in it aren't mentioned on the release notes page.

For anyone else's reference, I'm doing the following

var metaData = Model.Value<SEOChecker.MVC.MetaData>("seoChecker")
var tags = metaData.AllTags.ToString();
//hack to fix rel canonical tag
var canonicalCheck = new Regex("<link rel=\\\"canonical\" href=\"([^\"]+)\"");
var canonicalMatch = canonicalCheck.Match(tags);
if (canonicalMatch != null) {
    var url = canonicalMatch.Groups[1].Value;
    tags.Replace(url, Model.Url(Culture, UrlMode.Absolute));
}
@Html.Raw(tags)

SEO Checker: 2.11.4

Umbraco: 8.18.9