weird smell/taste

I have had this machine for almost 2 years now and never had this issue. The last few times I made soda water it had this weird industrial citrusy smell and taste right after fizzing and a bunch of gas accumulates at the top of the bottle right on top of the water. The water is fizzy but tastes metallic/factory-like. I tried multiple different bottle, both plastic and stainless steel and the same thing happened. This started happening fairly recently after the last CO2 tank exchange.