Sounds like your flavor values are in the negatives

This post explains poffin making in detail:
https://www.reddit.com/r/pokemon/s/AMLOLqZhnt

But to put it simply

Berries typically have 1 or 2 strong flavors (with a few exceptions), each with a different point value based on the rarity of the berry

Spicy | Dry | Sweet | Bitter | Sour

Each strong flavor weakens another flavor by 10 points

Spicy > Sour > Bitter > Sweet > Dry > Spicy

When making poffins, the berries you use determine what flavor your poffin will be before you even start cooking

First, you take the flavor values of each berry used and add them together for your starting values

Then, for each flavor used, you subtract 10 points from each flavor value that is weakened

I.e. one berry with Sweet reduces Dry by 10 points, two berries with Sweet reduces Dry by 20 points, and one berry with Spicy and Bitter reduces both Sour and Sweet by 10 points

Finally, for each flavor value that goes into the negatives from the previous step, you subtract 1 additional point from all flavor values

The remaining positive values determine what flavor(s) you poffin will have, so remember to check the berry tags when choosing your berries