I've been dealing with TanTan both as a paying customer and a YouTuber. My new GR201 gravel frameset is currently in paint according to TanTan.
One thing I've noticed on their Instagram is all the frames they seem to genuinely manufacture themselves have videos showing the frames being pre-production stress tested, painted in their lab, and then fully built. This is especially true for newly produced frames which they specifically want to market to OEM brands first versus direct to consumer. Basically the videos highlight their manufacturing capacity.
The X68 seemingly came out of nowhere. No pre-prod testing and no custom paint options available. Of course they don't want to fully promote this frame for obvious reasons.
TanTan lurks this forum as we know. From their perspective they probably have no incentive to disclose where the frames came from. For all we know, owners/investors of these factories probably own shares in other (read: competing) factories and therefore have the ability to trade products/blueprints etc.
