Former hurdler here.
I too watched the video frame by frame. Not conclusive either way, but I do believe her toe hit the barrier. However I don’t think it caused the fall. She was tripping all over herself on the way down and her toe just barely hit the barrier as a result. A couple of observations:
1. Starting from the 6 minute mark, she went over three successive hurdles with her left leg leading and her right leg as the trailing leg. If she is right handed, it would make sense that that would be her more natural hurdling sequence. At least it was that way for me. You train yourself to hurdle with the other leg leading, and can become proficient that way too, but the motion is less natural. On the fourth hurdle, she went over with her right leg leading and her trailing. That is when she went down. (Coincidentally on the water jumps she seems more comfortable taking off with her left leg, planting her right foot over the barrier, and then launching herself over the water with her right leg. That too would seem to be more natural for a right hander)
2. She took off way too close to the barrier on the one that caused her fall. She had to go almost straight up and had a lot of vertical clearance on the barrier but lost forward momentum in the process. As she went down, it seemed like her right (lead leg) began to plant and push forward to regain momentum but because she had gone up higher than normal and her planting motion was a split second too early causing a loss of balance mid-air. Her loss of forward momentum also meant that her toe did not have time to pass the barrier and instead came down on it (however slightly). If her toe had not hit the barrier she might have been able to regain her balance, but it did and she didn’t.
Too bad for her. I’ve been a fan since her days at MSU. hopefully she’ll come back stronger.