Lamp post GFI

The light must be wired in ahead of the receptacle.

At any rate, you need to seal or protect the entire assembly from moisture

Is the GFCI totally enclosed /weatherproofed with an "in use" cover as required by code? It's not properly wired to protect the lighting circuit - that is OBVIOUS. (all lights should be on the "downstream" side of the GFCI device.)

Do you have a cover on the receptacle?

Maybe you could rewire the other two lights so they are in parallel with the first one, which seems to be connected in front of the gfi.

This assumes only receptacles and not lights have to be on gfi's.

Are lamps required to be on a gfi? I don't think so. The lamp next to my front door isn't. (I don't have any on poles.)

FWIW, I have a gfi receptacle on the front wall of the house and I plug in an extension cord to power the lawnmower. I leave the extension cord, including its socket end, lying in the grass all year, in the rain and under the snow, and in 15 years it's only tripped once. I'm not even positive it tripped that time because of the cord, since the bathroom receptacles are on the same gfi. When I self-test the breaker it trips.

Does not seem like a great idea.

Yeah. I saw that two places in Colombia.

There were "pirate" electrical outlets wired in directly to the power wires.

Figure out where the moisture is infiltrating the cicuit and repair it.

Per code the light doesn't need GFCI.

To OP, is it getting obviously wet? If so, fix that with a good box. If not, probably not worth worrying about, unless you need it working when it's damp. You could put the whole circuit on a GFCI breaker or if the circuit happens to flow through a receptacle in the house, you could put a GFCI in there, make the outside just regular receptables and it will protect them all. The only issue there is that then you have to go to the breaker or that other GFCI receptacle to reset it if it trips. But given the issue with false trips and moisture I'd go with having the GFCI inside.