see
Pedantic Grognard
Depends on what you mean by "the lore". There's a lot of stuff in the three SRDs (3rd, 3.5, and 5th) and the original/revised/complete Tome of Horrors that very clearly and distinctively originates in D&D, rather than, say, Tunnels & Trolls or Palladium Fantasy. It might not be "the lore" in a deep sense, but "there are ten major kinds of dragons in the world, with these colors, these basic personality traits, these breath weapon types, and living in these environments" is definitely D&D lore.They're based on 5E but they cant use the lore for starters.
(I went to a lot of trouble pointing out examples of those things back last year in OGL discussion threads, when all sorts of people were running around saying that the OGL had always been meaningless, a corporate trick, usually quoting the old Copyright Office guidance that "you can't copyright game rules, just their expression". I mean, sure, that's the black-letter law, but if you wound up in court, you'd quickly find out that an otyugh isn't a "game rule", it's a pretty specific expression.)