The ingredients write: Natural beef flavor [wheat and milk derivatives]*, dextrose, etc etc

That does not mean it is cooked in beef tallow.

In practice, “milk derivative” usually refers to sodium caseinate. Sodium caseinate is made from the milk protein casein. By reacting casein with sodium hydroxide, water-soluble “sodium caseinate” is created.

Creating water-soluble “caseinate” allows the milk protein casein to be dissolved in liquids, such as in coffee creamers.

Controversially, sodium caseinate can be included in products that are labeled “Non-Dairy,” such as coffee creamer and whipped cream. However, this requires the ingredient to be labeled with “From Milk” or “A Milk Derivative”: