I think a few have mentioned it above. It’s not so much bending at the waist, as your hips are not rotated back enough to activate the glutes. This probably is a ripple effect from inadequate hip drive and low leg recovery. Add in arm drive too. All 4 elements play together. Focusing on cadence can help these elements as for many, to increase cadence at hte same pace, you need a faster, snappier, higher leg recovery and hip drive, and more deliberate arm swing.
It’s a complex motion. One action impacts the others so you can’t really focus on 1 element, but you can do drills that over exaggerate one element, then when you put them together, they start ot click.
Like most things, repetition, frequency pay off. And avoid practicing bad form… ie, be careful with extended speed work and long runs as they encourage the use of poor mechanics as you fatigue. As you change muscle patterns, it takes time to but the specific endurance for that motion.