Not sure. If you’re following the guidelines suggested in the article you’ll want to avoid any plastic and look for paper/cellulose bags. It may say “Plastic-free” on the container.

The team found that cellulose tea bags work the best at adsorbing toxic metals from the water while cotton and nylon tea bags barely adsorbed any contaminants at all—and nylon bags also release contaminating microplastics to boot.

Tea type and the grind level also played a part in adsorbing toxic metals, with finely ground black tea leaves performing the best on that score.

But the most significant factor was steeping time: the longer the steeping time, the more toxic metals were adsorbed.