itch.io

Hmm I've never using unity before. I've search on google and found some with similar issue like yours, like https://answers.unity.com/questions/1599816/getting-rid-of-2d-collision-jitter.h... and https://gamedev.stackexchange.com/questions/185533/jittery-collisions-in-unity-2...

Both discuss about the same topic, you can read them and compare them with your own code. If it not work, you can just watch some youtube tutorials (unity has much about it) and try to rework the project.

A thing to remember is don't do it in rash, or else you'll get nothing. Keep calm and enjoy the process 😉