I once had 5 blueberry autos, grown in different batches, 3 of which grew normal. The other 2, not so much. They began normally enough, starting preflower at 3 weeks, but they stayed there. And stayed there. Finally I switched to 12/12 lighting and flowering took off. But it was too late. Both plants reached well over 6 feet in height and I didn't have anywhere near that clearance. That's how I learned you CAN bend the whole main stem quite a bit, slowly, gently. Massive yields. But not worth it. These 2 plants occupied almost all of the available space in a 4 foot by 4 foot tent, making working on them very difficult.
That's what extreme phenotype variation looks like. This is minor phenotype or environmental variation.
Good luck