Matched pair PNP usage
I was thinking to a kind of current mirror, but R2 and R3 are
different.

R2 and R3 are usually different in a current mirror. They can be the same of course.
The circuit looks like it will control the gate-source voltage to ensure the MOSFET won't be damaged if the input supply is too high and positive. It may be some form of transient overload protection for the PMOSFET. However, the use of a zener/TVS device on the 5 volt rail suggests that anything significantly greater than 5 volts on the left-hand port for any length of time over a few tens of milliseconds and there will be smoke.
However, the main function of the circuit is to protect the 5 volt output rail (on the right) should there be a reversed supply at the input port (on the left). The PMOSFET will turn off if that happens.