If there is only contains, that means API connector initialized it as a list. Since the API response is not gonna change, probably you have to change your logic a little bit.
A list of emails containing a single email is more or less same as an email field’s being equal to a single email value.
Ahhhh airtable and its many downfalls, this is why I always recommend other codeless backends besides airtable.
Something that might fix this problem is when you initialize the call for the “Owners” table, you should be able to change the type from single to list. Try re-initializing the call and in the popup that shows up with all the datapoints, change the ones you want as a list to list.