i don know if this is a bug but if you go right in the sand section then left immedately you get clipped into the sand block, although it acts like a ghost tile/block so it doesn end your run. so if it is a bug it not a major one.
Good catch! I've noticed that bug too, especially when moving quickly through the sand zones. It's actually a visual glitch. what's happening is that the browser sometimes can't render the tiles fast enough because of the falling sand animation. As you observed, it doesn't impact gameplay and purely visual. Just one of those little quirks that come with browser games unfortunately :(
On this note, there actually is a rare bug in the sand section that I've been unable to find the conditions for; if digging under a resource, sometimes the resource will disappear (not just visually) and will no longer be accessible/diggable. It's happened only a handful of times, so I apologize for not having more information. It's definitely some kind of edge case in the game's logic.
No worries, thanks for reporting all those other pesky bugs. You've seriously helped a ton already :) The sand is actually one of the more complex cell types under the hood, mostly because of the falling sand animation. That slight delay in how the sand settles can lead to a bunch of visual quirks and edge cases, especially since different browsers handle the animation timing a bit differently. I really appreciate the heads-up about the disappearing resource.