The FBI's raid of former President Trump's home in Mar-A-Lago has set off another wave of online rage among his supporters, putting tech giants on high alert for new efforts to undermine the legitimacy of U.S. elections.

Why it matters: Tech companies were caught flat-footed by the deluge of disinformation aimed at delegitimizing the election process and outcome in 2020. Now, amid intense regulatory scrutiny, they are trying to get ahead of a repeat.

Details: A slew of Big Tech firms debuted new midterm-election policies in the past week, designed to give political campaigns time to adapt to the changes as campaigns ramp up.

TikTok on Wednesday doubled down on its ban on paid political ads, including paid influencer content.

• The company said it's taking new measures to block influencers and advertisers from forming undisclosed paid political partnerships.
• It also launched its Election Center, an in-app hub with authoritative information about voting and the election, six weeks earlier than it did in 2020.

Meta on Tuesday vowed to remove any misinformation about voting and said it will reject ads encouraging people not to vote or calling into question the legitimacy of the election.

• As it did in 2020, Meta will block new political and issue ads during the final week of the election campaign.
• It also said that during that week, it would no longer permit any edits to ads that have been previously approved to run.

Twitter last week said it would beginning enforcing its civic integrity policy, which bans the most common types of misinformation about elections and civic events.

• It also labels questionable tweets and adds links to credible information or helpful context.
• The company said it will also begin rolling out "prebunks," or blurbs about accurate information about voting and the elections.

Yes, but: The media landscape has become so fragmented in recent years that even the most careful defensive tactics by the most popular social media firms won't be able to halt the spread of election misinformation — including the "big lie" that Trump won in 2020, a claim supported by no credible evidence.

• Cable news networks, podcasts, encrypted messaging apps, email, direct mail, and alternative social networks provide a huge breeding ground for misleading election information. And the spreaders of election denialism are very adept at navigating a sprawling and ever-changing media landscape.

The big picture: The shift in election misinformation online from mostly Russian, state-backed campaigns in 2016 to more domestic, fringe networks now presents social media firms with a difficult free speech challenge.

• Coordinated inauthentic behavior campaigns by state-backed actors are often easier to identify and stop than misinformation spread by everyday users.
• Twitter's decision to block a New York Post story about Hunter Biden's laptop from being shared in the month leading up to the 2020 election triggered a sweeping backlash from conservative users who felt that the company had censored the story for political purposes. (Twitter's former CEO later said that decision was a mistake.)

What to watch: More companies are putting resources towards combating election and voting misinformation in languages other than English, following revelations over the past year of election misinformation campaigns targeting Spanish-language voters.

• Meta said it's putting more infrastructure in place to show accurate information about voting to users in a second language other than English.
• Twitter's prebunks will be presented in English, Spanish and all other languages supported on Twitter.
• TikTok's Elections Center will include resources in more than 45 languages, including English and Spanish.

Go deeper: How the "big lie" spread