Sneaked is the traditional form as the past tense of a regular verb, dating back to at least the 1500s, whereas snuck only appeared as an irregular form in the 1800s and it’s not clear why. It’s very unusual for a regular verb to become irregular. Snuck is more common in US English than British English, although sneaked and snuck appear in both variants. Sneaked would seem more correct especially for British English.
Sneaked is the traditional form as the past tense of a regular verb, dating back to at least the 1500s, whereas snuck only appeared as an irregular form in the 1800s and it’s not clear why. It’s very unusual for a regular verb to become irregular. Snuck is more common in US English than British English, although sneaked and snuck appear in both variants. Sneaked would seem more correct especially for British English.