How did Xu Jiayu Just go a Best Time at Age 30?

Xu Jiayu has been around for a WHILE in the world of backstroke, he swam at his first Olympics back in 2012 and won his first world title in 2017. Now not ONLY is Xu still able to rank among the FASTEST backstrokers in the world but he also just went a new personal best in the 50 backstroke during the 2026 Chinese national swimming championships. But how fast did Xu Jiayu just swim? How much time did he drop? And what technical change did he make to go so much faster at age 30?