No, this is not your problem.
These are NOT resources loaded on your site, and shouldn’t cause any HTTPS/mixed-content errors. They’re merely pointers to external technical specifications.
To explain this further, let’s say you have a paragraph of text, and in this paragraph, you have a hyperlink to the URL
http://www.example.com, like This is an example.
Yes, this is HTTP, but you’re NOT loading or embedding the resource or content on your site: you’re merely linking to the URL. And mere links should NOT create a mixed content error.
As to the GSC error itself, please take a look at Google’s official support article here: https://support.google.com/webmasters/answer/11396518