The 2D Physics of my game became jittery after upgrading to a new Unity version.

As the title states, the physics of my game changed after upgrading to 2021.2.19f from 2020.1.2f. I didn't make any other changes to the game whatsoever, and I made sure that everything physics related is done in FixedUpdate (the simulation setting in the project settings is also set to FixedUpdate). I opened a backed-up version of the game to make sure the settings were identical, and still nothing works. Are there any new features in 2021.2.19 (or any versions above 2020) that may be unintentionally affecting the game physics?