Many other people on sanctions lists, however, remain active on Facebook and Instagram, including President Nicolas Maduro of Venezuela and many in his government. But the move against the Chechen leader — despite his violent background — is only the latest in a seemingly arbitrary and often opaque decision-making process that has drawn criticism of the social media giant.

Facebook has been pilloried for allowing the spread of fake news on its platform and its limited response. In this case, it says it’s legally obligated to act because of financial sanctions, a standard that has not been evenly applied and which experts say may not be defensible.

“This sanctions law, which was written for one purpose,” said Jennifer Stisa Granick, a staff attorney with the American Civil Liberties Union’s Speech, Privacy and Technology project, “is being used to suppress speech with little consideration of the free expression values and the special risks of blocking speech, as opposed to blocking commerce or funds as the sanctions was designed to do. That’s really problematic.”

Facebook, which also owns Instagram, does not have a comprehensive set of rules for dealing with the removal of accounts or posts, relying instead on an often confusing set of “community standards” as well as on an algorithm and users’ reports of impropriety on the platform. Being on a sanctions list does not currently appear as a violation of posted community standards.

Now, Mr. Kadyrov — and the Russian government — want answers from Facebook about its reasoning.

‘Do 4 million followers mean nothing?’

In a tweet on Wednesday, Mr. Kadyrov said Facebook had told him that the accounts were deactivated because he had just been put on the sanctions list.