Should be a 130 model. Hard to see, but the oil is barely visible. It's not coming from the drain plug (that's where the green tape is), but from one of the water intake holes. That means either the internal water channels have corroded away or the gasket between the leg and the gearbox has failed. Or someone tried to clean the water passages with a drill or some such.
You can try and fit a borescope inspection camera in there if it fits and maybe see which problem it is, but either way the saildrive needs to come out and the leg split from the gearbox. Maybe the service (replacement of the rubber diaphragm and also the gasket in question) is due anyways.