See this article for details:
https://gizmodo.com/dnd-wizards-of-the-coast-ogl-1-1-open-gaming-license-1849950634

This will almost certainly be fought out in court, so this market will resolve on what the legal consensus is at closing time, or if that legal consensus arrives early by e.g. a terminal court decision (Supreme Court would do it, but lower courts deciding and the losing side just giving up the fight would count too).