Yes, that's exactly what pseudoanonymous means. It's fake-anonymous. It can be trivially de-anonymized.

No, "pseudoanonymous" doesn't mean anything, because it is not a word.

https://en.wiktionary.org/w/index.php?search=pseudoanonymous...

It is interesting how GitHub sort of prominently features this non-word in their article. Perhaps some South Asian or European person for whom English is a struggle.

There is no word that means "fake-anonymous". I would assume that the author of this article intended to write "pseudonymous" which is a real word with a real definition.

https://en.wiktionary.org/wiki/pseudonymous

But it would also be interesting if they very much intended the ambiguity of using a non-word that is more than it seems on the surface.