Blood & Treasure used advantage/disadvantage before 5e did, and I seem to remember the author being nonplussed (its original meaning) when it showed up in 5e (somewhat different, but the same concept).
Backgrounds were in more than one OGL game, but OGL Ancients comes to mind as one of them. Also Blue Rose
Flaws was actually released as open content by Wizards themselves, in Unearthed Arcana, though not in the 5e sense (more like anti-feats) and I can't find anything like Ideals or Bonds. But the general system of Ideals/Flaws/Bonds seems to be lifted from other games.
I had a feeling I'd seen advantage/disadvantage and backgrounds in OGL, thanks for confirming it.
Where do you think Ideals/Bonds come from?