This report is about Gnus and file lisp/gnus/message.el in particular.

There is a news server, namely eternal.september.org, which adds
Injection-Date and Injection-Info headers to messages. When superseding
such message the sending fails because the server does not want user to
fill those headers, the server wants to do it. Supersede works if user
removes those headers manually.

So, I suggest adding the headers to message-ignored-supersedes-headers
variable like the attached patch does.