Oh yeah sorry for goofing the link. 😅 And thanks for sharing the info
Windows does (and should) have vsync by default. All games should have an Exclusive Full Screen option! Not only does it bypass OS vsync but it avoids other issues with having to share drawing between other windows, basically just maximizes frame stability. Obviously, some people prefer the borderless window option too.
Regarding the damage avoidance issue, my recommendation is to create some levels or level segments that are more challenging, and playtest those thoroughly (especially with people who don't have preexisting knowledge of all the subtleties of the mechanics). Putting players up against more challenging scenarios will do more to reveal weaknesses in the design that are easier to overlook when the player isn't in much danger of dying. This is the core of the game so critical to get it right (the rest of the game feel is already feeling great).