Most tea bags that you purchase anywhere use some level of plastics in their component materials and/or binding (especially this latter). The only safe options are metal strainers that you filter the tea with (and that hopefully don't have coatings on them that are harmful... boiling a new one would not be a bad idea before first use) or just loose leaf.

Mesh tea bags, like are used at Starbucks, are plastic.

“The tea bags used for the research were made from the polymers nylon-6, polypropylene and cellulose.”

They aren’t pure plastic.

Those were three different bags, not all in one.

bourgie brands of tea come in little nylon pyramids instead of the normal paper/cloth bag.