HELP why is my recent Oatly reacting with my coffee???

I have always steamed my full fat Oatly and added it to a double shot of espresso and it tastes great.  I bought a new carton the other day and the first few sips were fine then it tasted like fish oil, or rancid oil WHAT IS UP?  Has the formulation changed?  Has anyone else experienced this?  This was a brand new carton with a November 2024 expiration date.  Is it possible this was not kept cold while in transport or it was not sealed properly.  What could explain this disgusting taste only after mixed with coffee!  On its own it tastes fine????