This is caused by insufficient support under the whole chin, incorrect slicer settings and the fact that the chin is an overhang than isn't connected to the model at the lower layers (this means that an island is printed in a sea of support that later becomes a peninsula).
The model is a Pokenmon called Dragonite which was found on Thingiverse. When sliced with the tree support option (note that tree support has been an advanced experimental option probably due to the issues with this support type) Cura builds a tree-like structure of which the stem/branch spreads out just before printing the island of the chin:
The problem is that the created support isn't enough for the print settings you are using. E.g. from a different view, you can see that part of the chin is unsupported with this support (note that the chin is also pretty flat, so each consecutive outer wall of each layer doesn't have the best contact with the previous layer, this is something you encounter when you print a sphere or rounded corners, that is why chamfers are preferred over rounded corners on bottom layers):
As seen in the latter image, there is quite some distance of the outer wall perimeter that is printed without support and minimal adhesion to the previous layer.
To deal with this you need to dial in the printer for this filament, i.e. do not print too hot, and use sufficient part cooling. Also be aware that you print the inner walls before the outer walls. You can also choose a different type of support, but that could result in supports that are stuck to the model, which are not easy to remove and possibly leave scars. Rotating the model around the X-axis can also be an option I've used successfully on printing miniatures.