When you load Canvas and Better Barrels, the little nob has a z-fighting issue:

Minecraft: 1.16.5
Better Barrels: v1.0.1
Cancas: v1.0.1267

Does this only occur in a certain direction?

Up or down seem fine, but the outline is borked (if you look closely, the knob is actually left of the outline):

The other directions don't matter:

I never realised the hitbox being in the incorrect place.

However, if you notice the models for the horizontal placed ones are slightly different - they have one pixel sticking out a little bit more. I guess this is probably what caused that, though I probably would have realised if there was a bug like that - might be due to some rendering from canvas. I'll take a look at it later and get it done 👍