TL;DL (Too long, did not read) summary
Mastodon prefers pages with OEmbed tags, then it will fall back to JSON-LD Structured Data, then OpenGraph tags and finally it will use HTML tags.
Random ramblings and ravings of Richy B
Mastodon prefers pages with OEmbed tags, then it will fall back to JSON-LD Structured Data, then OpenGraph tags and finally it will use HTML tags.