@Blu Quirks evolving and changing under heavy stress is established canon plus this is 3 years and a training arc later. The lack of requirement for 3 limbs was explained in like chapter 8: it's like saying Deku learning to use OFA in just his finger was a retcon. Plus SGB already showed his quirk was smthn to do with repellant and attractive force while SGKB built on it gaining strength to foreshadow this it rly just seems like a combination of his hopping and SGKB but from his feet this time.