Going backwards in terms of gear age does have a relearning curve it seems. For years now, new Canon lens designs have hoods that snap into place and you have to push a button to release them. I've become accustomed to that security when out walking around with lenses on the camera.
Older lens hoods are much easier to bump with your arm which will knock them askew. Petal shaped hoods only block what they're supposed to when they're aligned correctly.
I had adjusted the hood after noticing it but kept knocking it. I need to get in the habit of checking the hood each time before I shoot. Here are some examples from this morning.