More reputable sources than darkmoney.org, a site that lists no other sources and begs for money on every page.

https://www.cnn.com/2020/11/27/politics/dark-money-democrats-joe-biden/index.html

https://www.theatlantic.com/politics/archive/2021/11/arabella-advisors-money-democrats/620553/

https://www.bloomberg.com/news/articles/2022-09-20/biden-democrats-press-gop-to-end-secret-political-donations

Here’s three, and here’s one from your supposed “source”

https://www.opensecrets.org/news/2021/03/one-billion-dark-money-2020-electioncycle/