We have 937 products in feed and 168 disapproved.
I’ve just done a google search console report for one product, our SKU602 and it says :

4 warnings

Missing field “review” (optional)

Missing field “brand” (optional)

Missing field “aggregateRating” (optional)

No global identifier provided (e.g., gtin, mpn, isbn) (optional)

 
We had a similar problem when we first launched the feed and I wonder if your fix has gone wrong somewhere.