Ask whoever created this schematic.
You are right, it looks dodgy. The circuit to the left of the blue line is a double-cascoded NMOS current mirror followed by a double-cascoded PMOS current mirror. The lowest NMOS pair both have their sources grounded and their gate potentials equal, so they conduct the same current (or a ratio equal to their channel width ratio). The rest works in common gate mode.
The only way this could possibly make sense is if the transistors are of different construction, perhaps (?)
I'm not familiar with CMOS so can't tell if that makes sense. I think it wouldn't make sense in bipolar, but CMOS is more varied.
edit
Maybe the current source shown on the schematic is supposed to be temperature-dependent already, its implementation being left as an exercise for the reader.