A great example of gluten yeast extract can be found on Aromat spices, where the label reads “yeast extract (gluten from barley)”. If the label doesn’t specify the source of the yeast extract, we can assume it is not made from a common allergen like gluten.

Here is a link to the Aromat post for easy reference:
https://celiacsafe.co.za/2021/01/27/featured-product-aromat-seasoning/