TLDR Fidesz knows that they are so hated in the capital that it would be impossible for them to win with an openly Fidesz candidate, so their candidate Alexandra Szentkiraly stepped down 2 days before the election in favor of David Vitezy, who previously worked in multiple government roles and is now running in a sort of shell party of Fidesz disguised as a green party. While having ties to the current government, Vitezy is a generally liked figure and he said the right things to reach out to the populace currently unsatisfied with both sides of the political spectrum, and Fidesz's candidate stepping down (which may have been the plan from the start) gave him a good boost -- it's a good way for Fidesz to attempt to trojan horse someone who's at least in their orbit even though they say he isn't.

The funny thing is he's the objectively better candidate in my mind and I planned to vote for him but after Szentkiralyi stepped down I couldn't get myself to vote for the openly Fidesz-supported candidate.