Looks like we have incorrect defines on a few 2020 versions.

UNITY_2020_1_OR_NEWER is NOT defined on 2020.1.x
UNITY_2020_OR_NEWER is defined on 2020.1.x
UNITY_2020_1_OR_NEWER is defined on 2020.2.x
UNITY_2020_OR_NEWER is NOT defined on 2020.2.x

To repro, try this on a few 2020.x.x versions and make a MonoBehaviour with something like this in OnEnable

#if UNITY_2020_1_OR_NEWER
Debug.Log("UNITY_2020_1_OR_NEWER");
#elseif UNITY_2020_OR_NEWER
Debug.Log("UNITY_2020_OR_NEWER");
#else
Debug.Log("neither");
#endif