Most prop masters I’ve worked with use either this brand or something very similar. From that page the ingredients listed are: Marshmallow Leaves, Red Clover Flowers, Rose Petals, Fruit Juices, Honey. You can also buy packs that are designed to look like real brands(yellow american spirits, the famous “Marlboro Red”, and white for marb lights.)
Fake cigarettes have been pretty common props for a while now. Obviously there used to be a lot more actual tobacco use on sets but nowadays, especially with a lot of municipalities outlawing tobacco smoking indoors in public spaces, its almost always all fake/herbal. There are also nicotine free vaporizers that are styled to look like real cigarettes.