The problem is that I updated to unity 2020.3.15f2 and then opened a project that was edited in the version before that and everything works fine but visual studio says that everything is wrong, it doesn’t recognize Vector3, Transform, MonoBehaviour and everything else. I already try to reinstalled but that didn’t help to solve the problem. Any Solution to this?
Nevermind! After creating a script from unity and opening it, now has all references!
This falls under the second line below:
This may help you with intellisense and possibly other Visual Studio integration problems:
Sometimes the fix is as simple as doing Assets → Open C# Project from Unity. Other times it requires more.
https://discussions.unity.com/t/778503
Also, try update the VSCode package inside of Unity: Window → Package Manager → Search for Visual Studio Code Editor → Press the Update button
Also, this: https://discussions.unity.com/t/805330/7