This is not the first time I've ran into this issue as I noticed it on another model I was working on that I recently scrapped.
I have read on another topic that there has been a mess issue with shape generators and I think the issue I'm having might be similar. The model I've been working on is mostly the basic spheres you can use in TinkerCAD and I noticed with some of the spheres in a certain section there is a glitch where you get a triangler shard stilling out of part of the shape.
Glitch with current model
The glitch is only happening with the 'tail' of my model as its built with several spheres and cylinders grouped together. When I ungroup them the glitch shards go away. On top of that the glitches only happen in two different spots from two different viewings.. The lower one is from the Preview Viewer while the top on is from the actual editor and the glitch didn't occur when I made that part of the model the first time around. I will also note that the shard in the image on the right is FLAT and is sticking out of the sphere and not the cylinder.
Glitch from a model that now no longer exists
This was my first encounter of the glitch and it was how I pinpointed that it was the spheres. The model here was made in different sections but where the glitch occurs is where two spheres connect to a thick torus that has been 'shaved' by hole cubes. I've ungroup the spheres off the torus to see if that was the problem then regroup the spheres alone only to have the glitch there show up when I grouped them off the torus as well.
I need to find a solution to this issue before I request any more prints of the top dark brown and white model.