Raycast collisions being detected along a non-existent curve(?)

I have written a brief amount of code for debugging purposes to show visually when the player is on solid ground or not. The code can be seen here:

 private void UpdateCastValues()
     {
         //Casting
         Ray2DBegin = ((Vector2)transform.position);
         Ray2DEnd = ((Vector2)this.gameObject.transform.position + (Vector2.down * 0.75f));
     }
 
 private bool IsPlayerGrounded()
     {
 
         try
         {
             if (CheckHit().collider.tag == "ground")
                 return true;
             else
                 return false;
         }
         catch
         {
             return false;
         }
     }
 
 private RaycastHit2D CheckHit()
     { 
         hit = Physics2D.Raycast(Ray2DBegin, Ray2DEnd);
 
         return hit;
     }
 
 private void OnDrawGizmos()
     {
         if (IsPlayerGrounded())
             Gizmos.color = Color.green;
         else
             Gizmos.color = Color.red;
 
 
         Gizmos.DrawLine(Ray2DBegin, Ray2DEnd);
     }

Here we can see the player, which has a square collision box. Below the player is a Tilemap with a TilemapCollider2D component.

As you can see in the above image, when the player moves to the left, the gizmo turns red, indicating that there is no "ground" collision below the player, however, the player remains moving horizontally across the ground, as the relationship between the player's collision detection and the ground registers as a perfectly straight line.

The reason for this is because the collision for the Tilemap below is registering along a curve. I will show this in the picture below.

If you will excuse the shoddy drawing, by moving the player around and checking when the gizmo goes from red to green, I have identified a curvature being detected basically where I have drawn. It it goes from below, to higher up, and then below the tilemap.

This makes no sense to me. This is a first game for me so any help is appreciated.