I’ve never seen flex like this. Is it a defective installation? Looks like the far end is corroded, and it must be dissimilar metals.
Those are listed appliance connectors. I don’t see them connected to appliances. The use would be inconsistent with their listing.
The black flex is for connecting appliances? It’s huge.
I can’t speak to that one specifically, but they do make high BTU appliance connectors. Isn’t that a label on the far end of it? I have every confidence that they are not intended as a flexi union between sections of the structure piping.
This is a photo that was sent to me, so I don’t have a shot of the tag.
Any appliance connector is supposed to be listed and labeled. If you don’t see a label, its a code violation. I think it’s an appliance connector, although used incorrectly (and unlabeled).