Closes [13709](https://github.com/vercel/next.js/issues/13709).
The solution works, **(tested and confirmed with true and false flags with the latest next version)** though I am quite sure this is not the most elegant and proper way to implement it. I have spent the good part of yesterday and today's morning in order to make it more generic but since it's my first time working with anything related to webpack I have struggled miserably. Last, but not least I'm unsure if this is the most proper naming for the flag.
Please, let me know what you want me to change and I'll get it done asap.
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