Ruby 2.7.2 vs. 3.0.2 discrepancy

ruby_3_kwargs_error.rb

# This file runs fine in Ruby 2.7.2 and errors out in Ruby 3.0.2 with:
# testkwargs.rb:15:in `method_missing': no implicit conversion of Foo into Hash (TypeError)
#         from testkwargs.rb:31:in `<main>'

class Helpers
end

class Foo
  def wee(a=1, b:2)
    puts a
    puts b
  end
end

class Bar
  attr_accessor :helpers
  def method_missing(method, *args, **kwargs, &block)
    if helpers.respond_to?(method.to_sym)
      helpers.send method.to_sym, *args, **kwargs, &block
    else
      super
    end
  end
end

foo = Foo.new
meth = foo.method(:wee)

m = Module.new
m.define_method :wee, &meth
Helpers.include(m)

bar = Bar.new
bar.helpers = Helpers.new
bar.wee