This version of Unity is unsupported.
Removed

Physics2D.alwaysShowColliders

Obsolete Physics2D.alwaysShowColliders is deprecated. It is no longer available in the Editor or Builds. public static bool alwaysShowColliders;

Description

Enable to always show the Collider Gizmos even when they are not selected.

This is only used in the Editor to control Gizmo options.