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The link goes to "Free Trump Gold -> wewillbegreatagain dot co". I didn't bother clicking the link, but I searched and found that this scam ad has been in existence for over a year.
I'm no lawyer, but I would be really surprised if this obvious attempt to ride on someone's name/(in)fame was legal. Surely Trump could sue this person for what they are doing. Surely normal people have flagged this ad to YouTube, but it's still up.
When searching for details about this particular ad, I read about general frustation people have with the vast number of scam ads on Truth Social. But that's a whole other topic...