German Eurosports commentators said the following, and I think so too: IF a skater is too close to the boards or consistently almost crashes into them, it's a sign of insecurity. Meaning, in the set up of the jumps, there is that moment when you actually decide, I'm jumping. If you are not confident for whatever reason, that moment perhaps lasts another half second. In that half-second, you remain in motion of course. So that hesitation costs time and bam, now you jump, but you hesitated. That's why you're too close to the boards.
I believe this explanation makes sense. You can actually see it in Boyang's expression, that he begins to 'think' and then it's 'almost' too late.