Only now, because they were forced to lower it. There is nothing stopping them from raising it again, once the prospects of antitrust prosecution disappear.
For context: Epic launched their lawsuit in August 2020, fighting the 30% cut, and less than 3 months later Apple lowered it to 15% for small businesses. Absolute coincidence, I'm sure.
I guess that depends on your definition of "forced". In my recollection, the wave of bad press was so big that they really had no choice but to give ground.