Wow. That looks like a leak I just fixed in my backyard hot tub. In mine, the connection to one of the pumps had corrosion, and leaked. I took the hose off of the fitting, (like in your photo), and cleaned it and replaced the hose clamp,(that’s what actually failed, it had rusted to nothing), it would not have found the leak, until I ran the pump.
See the similarities? Now that it’s all, open, run various water sources and see if a drip appears, as it doesn’t look too serious, right now.
Old connections often fail. The one on my spa was 20 years old before it leaked.