Gens. Dwight D. Eisenhower and George C. Marshall at the Algeria Conference
There’s an issue with this photo. Do you see it?
Hint: Look at their uniform collars.
“Uniform” means everything should be worn the same, which isn’t happening in this photo.
Most generals wear stars on both collar points.

Gen. George Patton

Gen. Douglas MacArthur
Sometimes, Gen. Marshall wore his stars on the right, as above, but sometimes on the left.

Gen. Marshall and Gen. MacArthur December 1943
I did some research, but didn’t find anything specific on the wearing of stars on the collar of the Army uniform.
Maybe when you’re a general, no one tells you how to wear your insignia.
Photos from the George C. Marshall Foundation.