rubocop: Naming/MemoizedInstanceVariableName Cop doesn't work with methods that have a leading underscore

jekyll/convertible.rb has a private method named _renderer which memoizes using the ivar @_renderer as follows:

    private

    def _renderer
      @_renderer ||= Jekyll::Renderer.new(site, self)
    end

---

Expected behavior

Rubocop should not flag the above code when I configure the Naming/MemoizedInstanceVariableName with the provided directives for EnforcedStyleForLeadingUnderscores:

Actual behavior

1. Configured with EnforcedStyleForLeadingUnderscores: disallowed

Naming/MemoizedInstanceVariableName:
  EnforcedStyleForLeadingUnderscores: disallowed

Offenses:

lib/jekyll/convertible.rb:244:7: C: Naming/MemoizedInstanceVariableName: Memoized variable
@_renderer does not match method name _renderer. Use @_renderer instead.
      @_renderer ||= Jekyll::Renderer.new(site, self)
      ^^^^^^^^^^

1. Configured with EnforcedStyleForLeadingUnderscores: required

Naming/MemoizedInstanceVariableName:
  EnforcedStyleForLeadingUnderscores: required

Offenses:

lib/jekyll/convertible.rb:244:7: C: Naming/MemoizedInstanceVariableName: Memoized variable
@_renderer does not match method name _renderer. Use @_renderer instead.
      @_renderer ||= Jekyll::Renderer.new(site, self)
      ^^^^^^^^^^

1. Configured with EnforcedStyleForLeadingUnderscores: optional

Naming/MemoizedInstanceVariableName:
  EnforcedStyleForLeadingUnderscores: optional

Offenses:

lib/jekyll/convertible.rb:244:7: C: Naming/MemoizedInstanceVariableName: Memoized variable
@_renderer does not match method name _renderer. Use @_renderer instead.
      @_renderer ||= Jekyll::Renderer.new(site, self)
      ^^^^^^^^^^

All of the above scenario flags the variable @_renderer and suggests using the same variable @_renderer instead.

---

RuboCop version

$ rubocop -V
0.58.0