Hey, here's a list of things that I perceived as having different pixel sizes / density
- The edge of the water and sand seem to have different densities (some gains looks considerably smaller than the edge of the waves)
- Whirlpools seem significantly smaller with their pixels than everything else
- The duck's pixels also seem to be smaller than some of the obstacles or waves
Those were the major ones I noticed, but without being able to pause the game, it could just be imagination. I don't know your level of familiarity with Unity (so you may already know this), but you can keep the size of pixels consistent by setting the pixel amount per unit to be the same across all objects.
Other improvements would have been thins like pause menus, though I realize you may have added them in, but had them not work with the web build because your key binding was overridden.