Library build output different since 5.22, variable undefined

Bug report

What is the current behavior?

I build using the following output configuration:

output: {
	filename: './js/react/[name]-src.js',
	library: ['RF', '[name]'],
	libraryTarget: 'var',
	path: outputPath,

This results in a variable RF which is undefined.

The declaration of a property of RF now occurs using the following code (generated):

var RF;
(self["webpackChunkRF_name_"] = self["webpackChunkRF_name_"] || []).push([["audit-trail"], {

If the current behavior is a bug, please provide the steps to reproduce.

What is the expected behavior?

In versions of webpack before v5.22 (up until 5.21.2), this resulted in an object ‘RF’ being declared, where (as in the example above) the following would be available RF['audit-trail'].

The same file resulted in this before 5.22

var RF;(RF = typeof RF === "undefined" ? {} : RF)["audit-trail"] =
	(self["webpackChunkRF_name_"] = self["webpackChunkRF_name_"] || []).push([["audit-trail"], {

Other relevant information:
webpack version: 5.22 (also tried 5.23)
Node.js version: 15.7.0
Operating System: Windows 10
Additional tools:

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