I'm sure they know that will potentially lost a lot of revenues here. We all know that putting ads is very profitable as well, so banning them will surely hurt them that's why they are restructuring it in June. They don't need a total ad ban, but at least policies that will be both beneficial to each parties.
What means "a lot" in percent of their ad business? I didn't find anywhere an estimative value, but I do not think crypto related ads represents even one percent of their volume.