Boss, good day!

This isn't really a bug, more of a current limitation of the mod, although it could be considered a minor bug...

Right now, only the -1 and -2 pipe levels underground are highlighted in different colors, while -3 and subsequent levels are highlighted the same as the -2 level. If you feel like implementing it, would it be possible for different pipe levels to each have their own color — maybe random, or fixed?

Although we can't dig below sea level, if we run a pipe from a higher elevation, we can achieve multiple levels that way, not just 2. I've attached a screenshot.

Anyway, this is just something to think about, since it doesn't really affect gameplay.

As for the screenshot — that's where the minor bug comes in.

The thing is, the pipes at both ends are buried at -1 level, but during the transition, 2 of them end up going under what looks like -2 level in some spots, and accordingly they are highlighted as if they were fully at -2 level, even though in reality 99% of the pipeline route is at -1 level. This is more of an exception to the general picture rather than a recurring in-game situation.