Short answer
This is a mild risk. Watch your cat for signs like vomiting, diarrhea, or acting unusually thirsty in the next 24 hours. The main concerns are the high salt and any garlic seasoning. Just keep the deli meat away from all your pets in the future. If your cat shows any worrying signs, call your regular vet for advice.
Deli meat — Food safety facts
Feed with care · Cats · full breakdown on the linked food page
Salt and preservatives, and some are seasoned with garlic. A small piece as a treat.
The full verdict, portion guidance and serving notes are collected on the Deli meat food facts page.