I didn't see the game, but if the defender doesn't have their arms straight up and down, it's much more likely they'll be called for a foul, even if the offensive player creates the contact.. Doesn't matter if they had their arm out at 45 degree angle before the offensive player arrives, but the concept is basically the defender has to give the offensive player their 'cylinder' and move their arm out of the way (or at least back to vertical) before contact is made.

Defensive players are also generally allowed to jump straight up (again keeping arms vertical). Any time they jump to the side or backwards/forwards and there is contact there's a decent chance they'll be called for a foul.

It's quite the contrast to the mugging that most refs let defenders get away with against post-ups and dribble-drives before the shot but it's been a common thing I've noticed over this season