Certainly a big gain. More surprising, to me, is that Trump made little to no gain with black voters. He seemed to make a big effort for this group, and his endorsements from people like Lil' Wayne got so much publicity
IIRC, Trump only gained 1% with AA voters. But since turnout skyrocketed across the board, Biden on net improved from 2016 by a noninsignificant amount.
Not only was the Trump campaign cheap pandering, but it was clearly and openly cheap pandering (see: the "platinum plan"). I hope they learned their lesson.
As far as vote share, Biden may have lost around 2 points compared to Clinton, but there was still 3P share involved - and while the 3P shift from 2016/20 among black voters was smallest across any racial or ethnic group because black voters didn't really mess around with 3P candidates in 2016 (probably another 1 point difference margin-wise), it was still consistently enough that you can see precinct swings in majority-black urban areas in every part of the country to Trump. In all, a 3-4 point shift nationally among black voters to Trump: enough to give Trump the strongest level of support in percentage terms and margins for any Republican since 1984.
Arguably the best place to look is the ATL metro: GA is one of only 2 states where both black population percentage
and raw black population were growing as of 2019 estimates (relative to 2010 Census), and raw voter turnout was much, much higher in GA in 2020 than in 2016 (~25%) thanks to AVR - and, well...
The "cheap pandering" as you called it worked: not only with black voters, but non-white voters at-large (especially if they weren't integrated within their local non-immigrant communities/natively speak English) and even formerly disenfranchised white groups (such as the Amish) as well. There was more or less a clear correlation between "how closely aligned are you with the media-presented norm of modern America?" and how much each said group swung to Biden (or not), regardless of race, ethnicity or even education.
2016-2020 Swing versus Demographics:
