Explain your thoughts then

Yes, you are shaming someone by telling them their usage of a word was used correctly but they shouldn’t use it because they should only write in English. Also, who would be offended? Chefs and servers would want you to use the correct word. If you ordered prime rib with gravy but meant au jus, you wouldn’t get what you ordered.

What makes it odd? That’s the name of the sauce so it should be used correctly. We could call it meat juice instead if that sounds more appetizing and appropriate for you.

Might not be hateful but shaming others isn’t cool either

You’ll see au jus listed with prime rib for most restaurant and catering menus so it’s a common duo. Also, isn’t au jus different from gravy? It’s not thickened like gravy.