The pair previously donated $300 million to help the U.S. election process deal with challenges related to the COVID-19 pandemic, for example, by funding voting equipment and protective equipment for poll workers.

In the post, Zuckerberg also hit back at lawsuits trying to block the use of the funds: "Since our initial donation, there have been multiple lawsuits filed in an attempt to block these funds from being used, based on claims that the organizations receiving donations have a partisan agenda. That's false," he said.

Zuckerberg and Chan's election infrastructure donations come as Facebook faces both regulatory scrutiny from Washington and pressure from lawmakers to protect against misinformation and other election-related abuses on its platform.