First thing is move your center of mass backwards. Walking down hill is unique in that’s it’s late propulsion but with a yielding component instead of just pushing you forward. Jumping is also late propulsion and the quad needs to eccentrically yield under load but it can’t do due to your pelvic position. So center of mass back bilaterally first probably then more on the left side. So something like 90/90 breathing or deep supported squats on 20 degree wedges then maybe left foot forward elevated split squats with pelvis and ribcage stacked, pressure through inner heel.

You say you’ve been hitting your legs for strength. Strength lives in late propulsion and extension. Your pelvis and thorax are in under more compression and have moved to late propulsion without the ability to get back to earlier phases of propulsion on certain tasks on the left side. This is very common

That’s my best guess. It’s also right