I'm also with phughes. What caught my eye is that you set saddle height using heel-on-pedal and then pedal toes down, which means you're reaching for the pedals. You're probably reaching when you do the heel-on-pedal test, which mistake is really common. I think the earlier comment about climbing in lower gears might be something to look at more closely. Most riders want at a 75-85 cadence when climbing. If you're running out of gears to be able to do that on 10%, get lower gears. It used to be a thing to have a small cassette, In time, most riders get over that.
When trying to get saddle height just right, I go out with an allen wrench in my pocket and mess with saddle height on a relatively gentle hill, say 5%-6%, until using my heel cups to pull the pedal back at the bottom of the stroke with my usual cadence feels powerful.
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