Версия пакета:
ruby-3.1.2-alt2.1.x86_64

Шаги воспроизведения:

# apt-get install ruby i586-ruby-stdlibs

$ cat > helloworld.rb <<EOF
class HelloWorld
   def initialize(name)
      @name = name.capitalize
   end
   def sayHi
      puts "Hello #{@name}!"
   end
end

hello = HelloWorld.new("World")
hello.sayHi
EOF

$ ruby helloworld.rb

Получаемый результат:

/usr/lib/ruby/psych.rb:13:in `require': /usr/lib/ruby/psych.so: wrong ELF class: ELFCLASS32 - /usr/lib/ruby/psych.so (LoadError)
        from /usr/lib/ruby/psych.rb:13:in `<top (required)>'
        from /usr/lib/ruby/rubygems.rb:609:in `require'
        from /usr/lib/ruby/rubygems.rb:609:in `load_yaml'
        from /usr/lib/ruby/rubygems/config_file.rb:360:in `load_file'
        from /usr/lib/ruby/rubygems/config_file.rb:189:in `initialize'
        from /usr/lib/ruby/rubygems.rb:331:in `new'
        from /usr/lib/ruby/rubygems.rb:331:in `configuration'
        from /usr/lib/ruby/rubygems/defaults.rb:85:in `default_specifications_dir'
        from /usr/lib/ruby/rubygems/specification.rb:869:in `load_defaults'
        from /usr/lib/ruby/rubygems.rb:1347:in `<top (required)>'
        from <internal:gem_prelude>:2:in `require'
        from <internal:gem_prelude>:2:in `<internal:gem_prelude>'

Если удалить пакет i586-ruby-stdlibs, то ошибки нет:

$ ruby helloworld.rb 
Hello World!

Аналогичная ошибка появляется так же и при запуске gem:

$ gem
/usr/lib/ruby/psych.rb:13:in `require': /usr/lib/ruby/psych.so: wrong ELF class: ELFCLASS32 - /usr/lib/ruby/psych.so (LoadError)
        from /usr/lib/ruby/psych.rb:13:in `<top (required)>'
        from /usr/lib/ruby/rubygems.rb:609:in `require'
        from /usr/lib/ruby/rubygems.rb:609:in `load_yaml'
        from /usr/lib/ruby/rubygems/config_file.rb:360:in `load_file'
        from /usr/lib/ruby/rubygems/config_file.rb:189:in `initialize'
        from /usr/lib/ruby/rubygems.rb:331:in `new'
        from /usr/lib/ruby/rubygems.rb:331:in `configuration'
        from /usr/lib/ruby/rubygems/defaults.rb:85:in `default_specifications_dir'
        from /usr/lib/ruby/rubygems/specification.rb:869:in `load_defaults'
        from /usr/lib/ruby/rubygems.rb:1347:in `<top (required)>'
        from <internal:gem_prelude>:2:in `require'
        from <internal:gem_prelude>:2:in `<internal:gem_prelude>'