I'm willing to broaden my definition of a snack to include anything that goes into my stomach.
More than one reference considers beverages to be a snack.
Don't get upset over newfangled uses for words, dictionaries are always being updated.
"CHICAGO — Consumers increasingly are reaching for bottled beverages to curb hunger between meals. Sipping soups and bone broths, plant-based lattes and cold-pressed juices are emerging as popular snack options, said Jill Houk, corporate research and development chef at Olam Spices."
https://www.foodbusinessnews.net/articles/12954-is-it-a-beverage-or-is-it-a-snack-the-answer-is-yes#:~:text=The%20answer%20is%20yes,-Source%3A%20Coca-Cola&text=CHICAGO%20—%20Consumers%20increasingly%20are%20reaching,development%20chef%20at%20Olam%20Spices.
This source considers water to be the ultimate snack because it says the body can confuse thirst with hunger.
And it also mentions fruit & herbal teas as being snacks.
Dieting is hard when you have to fight those cravings. ☹ But you can give in to them with these healthy snack ideas that keep you fit and full.
listonic.com
Earlier entymoloy of the word snack from the 13th century onward suggests that it was related to snout (a dog's snout) sniff, to breath, the bite of a dog, pant, nasal mucus, snatch, to take from someone's hands.
That's shows how the meaning of words can change over time.
"to bite or snap" (of a dog), perhaps from a Northern variant of snatch (v.) influenced… See origin and meaning of snack.
www.etymonline.com