When you ask a question on a public forum, it means anyone is free to answer. So I'm answering.
Many people started spreading rumours (based on nothing, no one ever gave any links) about Supermium being fully open source, and some even started to believe that, all until someone finally figured out: Supermium needs a special dll without which it doesn't work at all, meaning it's all close source in the end, I mean the whole browser.
What's so hard to understand or why are you having troubles to reconcile?
https://www.deepl.com/translator