The Bitten Sandwich has an appropriate 20% adjustment to its Health effect, due to the apporoximate 20% bite taken out of it, as seen in the item's 3D model, both when found in the game, and when viewed in the inventory menu. However, the Bitten Sandwich Value is not adjusted for the bite, and the Bitten Sandwich Mass is overly adjusted for the bite.
With the adjustment to Health and Mass, there is a clear intention that the Bitten Sandwich should have appropriately adjusted stats compared to the (non-bitten) Sandwich, they just weren't fully or ideally adjusted.
Sandwich:
Health: 5
Mass: 0.30
Value: 75
Bitten Sandwich:
Health: 4
Mass: 0.20
Value: 75
Bitten Sandwich - suggested more appropriate stats for 20% bite:
Health: 4
Mass: 0.24
Value: 60
This issue has been reported to Bethesda. Observed on Xbox Series X.

Attached Files:
Sandwich-Bitten-Sandwich.jpg