Main stem not growing

Has anyone ever seen this? The side branches have outgrown the main stem where the main cola grows. The side branches are huge compared to the main cola stem. Growing much taller . Leaving the main stem under the canopy. I have done no trimming or training techniques. I'm 3 weeks in. Hydro, 600W LED. Temps are good, nutes are good. It is a Auto flower Hindu Kush.

Somehow the main stem or top was damaged. Don’t sweat it at this point. Suggest regular or feminized seeds instead of autos. You’re on a timeline with autos and no time to allow for corrections.

Agreed ^^^ I can't think of another reason this could happen