When loading the application code with keystores 0.4.0 and gem jwt in version 2.3.0 the following happens:
ArgumentError: wrong number of arguments (given 0, expected 1)
ruby/3.0.0/gems/keystores-0.4.0/lib/keystores/jks/pkcs8_key.rb:63:in `block in <class:RSA>'
ruby/3.0.0/gems/jwt-2.3.0/lib/jwt/jwk/rsa.rb:85:in `new'
...
It works fine with jwt 2.2.2 so a temporary solution is to lock the jwt version to lower than 2.3.0