Same conditions and same validation check as in #2800 - Nu Html Checker (https://validator.w3.org/nu/about.html) which checks not the source code but the generated code ("Check serialized DOM of current page")

The validator throws the message:

Attribute href not allowed on element a at this point.

Thanks for your help!