To further muddy the milk/not milk waters. Oatly[1] appears to be grain, soaked in water, with enzymes added to break down starches into simple sugars.

Any brewer should know this is a wort, basically unfermented beer (without hops).

So there you go, you should really be asking for wort in your coffee.

[1] https://www.oatly.com/int/our-process