From this article – https://www.newsweek.com/plastic-tea-bags-update-avoid-harmful-release-2009157

What Is the Safest Way To Drink Tea?

Some tea bags are better than others if you want to avoid ingesting plastic. The tea bags studied by the Barcelona scientists contained polypropylene, cellulose and nylon, but there are many tea bags in stores which are plastic free.

To work out whether your tea bags are free from plastics, check the packaging. Plastic-free brands are likely to use this in their marketing, so check for labels such as “plastic-free,” “biodegradable” and “compostable.”

Another way to avoid plastic from tea is to switch to loose-leaf tea and a plastic-free tea strainer, such as those made from stainless steel.