RubyGems.org has deprecated the dependency API (api/v1/dependency), moving to the “Compact Index” API mechanism. More information on the deprecation process and concrete details can be found in this blog post. April 10th is a “brownout” period during which RubyGems.org returned 404s for the Dependency API. Additional “brownout” dates (the full list can be found here) will take place until the API will be deprecated completely on May 10th, 2023.