No, not usually a flavouring item per se.
firstly, make sure that just because the "product" says "Tea" on the pack, make sure that it actually contains Tea.
Some of the so called "flavoured tea's" are actually "herbal infusions" and don't contain any "proper" tea at all.
Plus, the problem with these "herbal infusion" type products, is that they often claim to have all sorts of properties and they don't, just a weak, watery taste that might have a hint of something in them.
The actual use of "proper tea" in meads is to provide a source of tannin. "Proper tea" has plenty of that. If I make an older recipe that uses tea, I'll either brew the tea (boiling water, don't forget) at 2 teabag per 1/2 pint of water (and I mean proper teabags designed for making the tea in a pot, not those piss weak "1 cup" teabags) or 2 teaspoon of loose tea per 1/2 pint of water, to ensure a nice strong tea with plenty of tannin (oh and that 1/2 pint is enough for 1 gallon).
@ FrayAdjacent, if you wanted some vanilla flavour, or at least a hint on it in a sack mead, then you'd be better placed using a whole, or part, vanilla pod, that has been cut to expose the tiny seeds in the pod. Or at least some "proper vanilla extract". Don't forget, if you did use a pod, alcohol is a very effective way of extracting vanilla flavour. Proper/natural vanilla extract is made from steeping pods in alcohol.
regards
fatbloke