Administrate was already compatible with Rails 7, but its specs weren't. After doing some fixes, there's a pending one that appears to be caused by strange Ruby behaviour when undefining constants on Ruby 3.x.
Specifically, spec/generators/dashboard_generator_spec.rb creates a number of classes and then attempts to undefine them, but these appear to linger around, affecting results at spec/generators/routes_generator_spec.rb.
I have tried a few things to no avail. In some attempts I could fix this issue, but new ones would appear.
From what I can tell, this affects the specs, but not real world usage.