This is an abstracted / generalized version of the flag of the Yenish people, found, e.g., here [1] on FOTW.
Different variants of this flag (with different other content added on top) can be found when searching for "Yenish flag" online, but the common feature appears to be the four triangles and colors.

This flag has no official status whatsoever. It is even unclear whether it was somehow adopted by representatives of the Yenish people, but at least a subgroup of them seems to use it as their flag.
Own work
Hierakares