Board Thread:General Discussion/@comment-11394256-20200923213100/@comment-9605025-20200924063323

FYI, mw:Extension:Display_Title describes what the extension is supposed to change. Keep in mind that this documentation is for the latest version; not necessarily what Fandom is using.

As for the percent encoding, that is probably because the percent decoding is done before determining what the pagename means. Whether encoded or not, you are asking the wiki for "Pokemon: MewYou!" and it knows there is the interwiki prefix "pokemon" so it assumes that is what you meant.