Meta boss Mark Zuckerberg says he regrets bowing to what he calls pressure from the Biden administration to "censor" content on Facebook and Instagram during the coronavirus pandemic.
In a letter sent to a US House committee chair, he said some material – including humour and satire – was taken down in 2021 under pressure from senior officials.
The White House has defended its actions, saying it encouraged "responsible actions to protect public health and safety".
Mr Zuckerberg also said his firm briefly "demoted" content relating to Joe Biden's son, Hunter, ahead of the 2020 election, after the FBI warned of "a potential Russian disinformation" operation.
It later became clear that this content was not part of such an operation, Mr Zuckerberg said, and it should not have been temporarily taken down.
Mr Zuckerberg did not give further detail about the actions he regretted during the pandemic. At that time, his business removed posts for a variety of reasons.
In 2020, he donated $400m (£302m) via his philanthropic Chan Zuckerberg Initiative which was intended to help government offices conduct the election during the pandemic.
However, misinformation spread rapidly on social media accusing Mr Zuckerberg of effectively using a loophole to skirt maximum donation limits in a bid to get Mr Biden elected.
Mr Zuckerberg said his donations "were designed to be non-partisan".
"Still, despite the analyses I've seen showing otherwise, I know that some people believe this work benefited one party over the other.
"My goal is to be neutral and not play a role on way or another - or to even appear to be playing a role - so I don't plan on making a similar contribution this cycle."
Mr Zuckerberg said the decisions made were the decisions of his business, but that the “government pressure was wrong”.
He continued: "We made some choices that, with the benefit of hindsight and new information, we wouldn't make today."
Mr Zuckerberg said he and Meta would be ready to "push back" if something similar happened in the future.
His letter was addressed to Jim Jordan, the chair of the House judiciary committee, which has been investigating content moderation on online platforms. Republicans said the letter was a "big win for free speech".
In a statement issued to the website Politico, the White House stood by its actions.
It said: “Our position has been clear and consistent: we believe tech companies and other private actors should take into account the effects their actions have on the American people, while making independent choices about the information they present.”
Mr Zuckerberg's comments on Hunter Biden refer to the story of a laptop that was abandoned by the president's son at a repair shop in Delaware - as first reported by the New York Post.
The newspaper claimed emails found on the computer suggested his business abroad had influenced US foreign policy while his father was vice-president.
The president and his family have denied any wrongdoing.
The story became a notable right-wing talking point in the US, and a point of contention as some social media platforms censored the content.
Mr Zuckerberg said the story was temporarily demoted on his platforms while going through a fact-check - after a warning from the FBI of a potential Russian disinformation operation, and "in retrospect, we shouldn't have demoted the story," Mr Zuckerberg wrote.
"We've changed our policies and processes to make sure this doesn't happen again."
Mr Zuckerberg also said he did not plan to make any more contributions to supporting electoral infrastructure.