That should be a clue. . Once you get it that fixed, check all fittings you can and inspect wherever you can, to include connections at hot water tank. That should be "hot" side because it is red. Hot has a tenacity to wiggle loose before the cold IMO. Inspect wherever you can, they do come loose. Inspect all the places you can to include connection at hot water tank, toilet valve and under sinks, showers. You don't know which of the fittings will work its self loose. I mark mine with a felt tip pen, index line type of thing so the next time inspecting I could see if fitting was coming loose.