that is not the first time I notice this. How do you think I can fix this?
Sorry, i dont remember if the delaunay 3d is a standart component… You need shortest path as well, to run this: coralgrowth.gh (10.9 KB)
ps. do not look at shortest path glowing red, the problem appears with any other components too.

Your curve inputs have some angles too small for the radius being used. It’s the same issue discussed here:

Multipipe is for creating clean quad subds, and to do this it needs to place edges and vertices at certain positions in the junctions where the pipes meet. If you have something like the situation on the right, where the angles and pipe radius cause them to completely overlap, there is nowhere sensible for these vertices to go without completely changing the topology.

In these situations you have a few choices - modify the input geometry to avoid such small angles, or usea different approach to the surfacing, such as Dendro, which will give you a much heavier and non-structured mesh instead of a SubD, but will work even with completely overlapping curves.