I knew superficially the concept of V-sync, but I didn't know that it only worked with fractions (/2). It makes sense when you think about the concept, which makes me understand the benefit and complexity of Free/G-Sync.
In the medium term, the way this game behaves on the Web won't matter so much, since the final version will have to compile an executable to be able to put it on Steam.
However, if I manage to get a publisher for the consoles, a port of the game would probably be done with a Unity browser running the HTML version of the game.
Anyway, maybe the V-sync is still in the executable. Would working with max frame 0 (unlimited) be a bad practice?
The monitor you used to test the game here at itch, is it 60hz?