Called a “buffalo patch” Make sure it is feathered out over a large area
I use a couple of 5 gal stir sticks
Drywaller’s have referred to it as a “California”, “Chicago”, and a Toronto patch. Never heard of it referred as a Buffalo patch! That’s OK, use what ever name you wish, the application works regardless of what name you give it!
Ive used them for a patch job, when there was no good alternative, but would not even consider them on a new project. They are remarkably strong, but not as strong as wood corners.