Sidebar showing on 404 page even after being disabled

Hi,
In my 404 page, I don’t want the sidebar to show. I specifically selected the layout No Sidebar for the page (theme: SiteOrigin North), and when I go to the actual page URL, the sidebar doesn’t show.
https://weignitegrowth.com/404-page/

But when I put in a random URL that doesn’t exist, for e.g. https://weignitegrowth.com/mm, and it redirects to my custom 404 page, then the sidebar shows.

How do I get rid of the sidebar then, and keep it the same layout as https://weignitegrowth.com/404-page/?

Thanks,
Poulomi

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