Wtf, hax. This changes everything.
I'm reading that you could do this in the first game, too. I completely cleared that game back when as well, and it never even occurred to me to try that.
Edit: Well, kiddos. I got to the part where it turns out doing this is mandatory. No spoilers, but I'm sure some of you know which part. I guess the bit right before that is what teaches you this, but I use the term "teaching" as loosely as possible. Still and all, knowing this several hours of gameplay earlier would have possibly saved me from several embarrassing perforations due to jumps fallen short.
From what I've been playing from the game, probably halfway through, mechanically it feels like Hollow Knight, but with several small additions and updates that make it seem distinct. Also, it feels like the dungeon designs prioritize what was added in Silksong and don't explain what was inherited from the previous game, though having in mind HK's mechanics can help somewhat frequently from my experience.
Also a tip: if you played HK and ventured deep in Deepnest, remembering mechanics more useful there can be specially helpful in Silksong.