Geez, sadly some people will never miss an opportunity to go after a skater of their choice and try to diminish them
Anyway, in my personal opinion, jumps as such, or jumps entries or exits, are not really signature moves at all, with maybe the exception of a delayed axel. In my opinion, a signature move is something a casual fan is able to notice, tell apart from other elements, remember and recognize the next time they see it, and that's how it becomes really associated with this particular skater for the general public. Speaking from experience, anyone can notice a hydroblade, a cantilever, an Ina Bauer, a spiral or a death spiral, etc. and tell them apart from other elements even if they cannot name them. This is also true for a delayed axel which is instantly noticeable as a completely different type of jump even for a layperson, even if they cannot tell exactly why. That's how it may become a skater's "signature" - Yuzuru Hanyu's, in this case.
OTOH, differentiating between lutzes, flips, regular axels, toe jumps etc., their number of rotations, or entries to or exits from them, is not really something a casual fan would notice or care for much unless really spectacular for some obvious reason - that's why I put delayed axels aside from all the other jumps. Same goes true for such features of a jump as speed, height, axis etc. I think if you have to measure it to tell the difference, it means
nothing for the general public attention and is of no interest to them at all. A move is "impressive" for a layperson or not, and that's it. Being it a signature move is not decided upon by a technical panel, but by the public at large, and their choice is much more concerned with aesthetics and it being "impressive" and "spectacular" than with it meeting any bullets that any expert could put forward.
Still, I'd say a backflip
is a signature move. No matter if you like backflips or not (I don't), they are easy to tell apart from other elements and noticeable and recognizable as such. So, yes, these are signature moves for Surya Bonaly, Adam Siao Him Fa and Ilia Malinin.