What Hypernova said. There was also a bug caused by GameMaker that would allow you to double jump just by holding jump, which was unintentional. I've tried to fix that with a workaround so it should be less confusing now.
Recent community posts
I used GameMaker: Studio for this so unfortunately what I can do to fix the issue is very limited, but I'm still pretty sure that the issue isn't just with higher refresh rate monitors since several others played the games I made with the same engine before. I'm pretty sure that at least one of them would also have a higher refresh rate monitor.
I even found a forum thread someone asking if that would happen and everyone's answer seems to be no: https://forum.yoyogames.com/index.php?threads/v-sync-question.40821
Oh damn thanks for the notifying me. I actually have a TV with a higher refresh rate connected to my PC, so I tried the game on it and it seems to run just fine. I've also never heard similar reports from anyone else, so it might have to do with your PC? Either way, I'll make sure to add a V-Sync toggle key to this and all my future games though, just in case.