JVM flag sets lower memory

Ok so a friend of mine got this OutOfMemory error.
I quickly found the solution with increasing the allocated memory, but somewhere else something sets a new flag as seen in the crash report after the "-Xmx2G" there is right at the end this flag "-Xmx256M". (line 73)
I have absolutley no idea where this comes from or how to delete it so...help pls.