Center yourself on standing climbs.
We often see riders make a mistake on out-of-saddle climbs. They lean way over the front of the handlebar, much more than necessary for the grade they’re on.
The result: Too much weight on the front wheel, which grinds the tire into the pavement and scuffs off speed. This actually makes the hill harder.
The trick is to stay back a bit and feel for the balance point. This is where your forward lean keeps your front wheel light while still letting you deliver strong pedal strokes.
Think about this on climbs when your front tire looks and sounds like it’s half flat. That might be unavoidable on super-steep hills. But on most climbs, you’ll go up with less effort if you find the sweet spot between your wheels.
If this were true then Caleb Ewan would not generate so much power in a far-forward position. Any “half flat” effect as you describe can easily be countered by increased tire pressure.