For me in google this was the first result - https://www.reuters.com/article/uk-factcheck-votes-counties-election/fact-check-clarifying-the-comparison-between-popular-vote-and-counties-won-in-the-2020-election-idUSKBN2931UY

And it says the same - Biden had won 509 counties and Trump 2,547 counties. Surprised it isn't shown better, you have to dig through the article