If I understood correctly, then the way you described it, is the correct way to do it.
Therefore, it’s not a workaround, but actually the right way to format it.
Putting a URL inside brackets like this [[https://forum.obsidian.md/t/graph-hide-external-links/9454]] is not the way Obsidian nor markdown works with URL which is why it was read as an internal link, beacuse [[this format]] is for internal links only.
But you already found the soution, I just thought it’d be useful to write this down for anyone else who might struggle with this in the future