This point also made me wary at first, but the way I understand it integrating the OpenGraph protocol for transaction previews should only lead to a "nicer" visual representation of the payment link when published via social media or sent via messenger.
What about if the Social media platform chooses to restrict certain previews?
Or individuals that wouldn't want their transactions preview shared to the public.
OpenGraph has become the de-facto meta-data standard for social media, including the fediverse, so you're not restricted to any one social network.
Also I assume the main use case for this would be crowdfunding campaigns like ICOs or the public sale of NFTs? Though I assume adding informational meta-data might have use cases for private transactions as well.