Details - if you are interested

Maintenance Policy for Ruby on Rails

https://guides.rubyonrails.org/maintenance_policy.html

As of Dec 25, 2021, Supporting Ruby 3.1 with Rails should not be security issues.

• Rails 7.0.Z accepts bug fixes.
• Rails 6.1.Z accepts security issues only.
• Rails 6.0.Z accepts severe security issues only.

Changes to support Ruby 3.1

• Add Class#descendants
• Psych 4 support
• net-smtp, net-imap, net-pop are bundled gems
• Ruby 3.1 performance optimization
• DidYouMean::SPELL_CHECKERS.merge!(error_name => spell_checker)' has been deprecated.

详情见原文： https://gist.github.com/claudiug/bdc2fb70b10d19513208c816588aed92