Sudden step failure without any change

Starting yesterday, this step for my project began failing on installing nokogiri:

An error occurred while installing nokogiri (1.10.10), and Bundler cannot
continue.

In Gemfile:
  rails was resolved to 6.1.7.2, which depends on
    actioncable was resolved to 6.1.7.2, which depends on
      actionpack was resolved to 6.1.7.2, which depends on
        actionview was resolved to 6.1.7.2, which depends on
          rails-dom-testing was resolved to 2.0.3, which depends on
            nokogiri

This happened without any change to my repo, so I'm assuming there was an upstream change that caused the failure? Did I miss a deprecation or mandatory upgrade?