The overly-simple explanation is that any experienced sitter should understand that anything within reach of a pet is at risk of being destroyed/taken. Especially groceries.
If a sitter is struggling financially and has taken amazing care of the pets on a long sit, and some very expensive things were damaged beyond repair, I can see how this can become a grey area in terms of how to actually resolve it.
Now that what’s done is done, all you can do is reply honestly to the sitter’s review of you. It might turn off some sitters, and the sitters who are prepared, or okay with the possibility of their stuff being destroyed, will be fine with it in the future.