Any shots right before the jump? I know that would be harder to get, but pointing to a divot after the fact is meaningless. It could have been a much smaller divot, and his jump made it bigger, or he caused the divot.
Not many people take pictures of the ice or only film the feet of a skater.

There were a lot of marks in this particular corner before (visible during Deniss' 3Lz+2T and Andrei's StSq), but it's hard to tell which of the marks was at the same spot Yuzuru attempted his 4S at. (There were some marks that did look suspicious, as in they looked more like singular divots than curves - but due to different camera angles, zoom and video quality, I cannot say with certainty 1) that they were holes 2) that they were at the exact spot of the jump attempt).
However, what I am rather sure of, is that this hole wasn't caused by an edge jump and very likely not by this particular jump attempt.
(For ease of explanation, I'm reposting this picture): Above and below the divot you can see the entry curve. The hole is almost star-shaped and has significant expansion in the direction perpendicular to the direction of the curve. Particularly the elongated expansion towards the left would not exist if this jump had caused the whole divot.
Furthermore, more generally speaking, edge jumps are much less likely to cause divots from their take-off (particularly divots of this shape) due to the force used to generate spring and rotation being spread on the full length of the blade.
Toe jumps, on the other hand, concentrate all of their force onto a very small part of the blade, the toe-pick. The force per area ratio is much higher, making it more likely for a toe jump to cause an actual divot. (And that is without taking into account that a good number of skaters use more force for their toe jumps than for their edge jumps).
(The higher force/weight per area ratio is also the reason why for example ice picks exist - the amount of force needed to break the ice is much lower if it is concentrated onto a very small area).
Whether it's bigger or not is hard to tell without being able to compare it to before, most likely some of the sidewards expansion and a part of the depth would be enlarged? (The force transfer in Salchows from blade to ice is more sideways-down than straight-down like with toe jumps)