Reproduction steps:
1. Open attached project
2. Open scene "mainscene"
3. Enter play mode
4. Click inside the Game window to focus it
5. Hover your mouse cursor close to the edge of the yellow sprite. Do not touch or hover over it
6. Look at the Console window
--- You should see that OnPointerEnter events are triggered.

User suggested a fix:
The offending Unity code, as found at https://bitbucket.org/Unity-Technologies/ui/src/fadfa14d2a5cb8d6462db067e669b4b2bc11a018/UnityEngine.UI/EventSystem/Raycasters/Physics2DRaycaster.cs?at=4.6
var hits = Physics2D.RaycastAll(ray.origin, ray.direction, dist, finalEventMask);
They propose changing that to:
var hits = Physics2D.GetRayIntersectionAll(ray, dist, finalEventMask);

This change also fixes case 725973