Amazing - both our rear window jets seemed to have developed the same issue in the same timeline.
It's probably just clogged rather than broken.
Regrettably I didn't take any pictures but it's very straightforward fix with no tools required. Everything can be done from the outside.
- Remove the plastic trim around the rear wiper hub by hand, gently lift around the edges to disengage the clips.
- Under the trim there is a small plastic L adapter (which contains the two brass nozzles) located on top of the main nut holding the rear wiper arm on. Gently prise this L shaped plastic off by hand. Levering up on one side is enough.
- Blast the inside of the adapter piece from the inside. I suggest using any cleaner fluid, like a glass cleaner in a spray bottle. You can hold the spray head against the piece to form a tight seal, then use the pressure to blast through the nozzle and clear any blockages. You should have 2 clear streams.
- Before you push everything back, get in the car, start ignition and activate rear window wash to blast out any more debris that might be within the tubing. If the hose is unrestricted, a clean jet of the washer fluid should shoot behind with a considerable height. (Obviously don't have anybody standing behind you while you do this lol or get a free facewash)
- Refit the plastic nozzle piece back on top of the wiper hub nut, it should just push on with some force used. There was no o-ring on my Formentor and it won't sit completely flush even after refitting, so consider this is normal. (See how loose it is before removing it the first time for some idea)
- Refit plastic trim around the hub, push on it until it clips back in.
