This article probably sums it up best as “inconclusive”
Polyester is a synthetic polymer highly prized for its strength, resistance to wrinkles or shrinking, and quick-drying properties. Its versatility and cost-effectiveness make it highly popular in the textile industry, and it is used extensively in apparel, home textiles, and various technical...
biobide.com
My own view is that polyester could be our “next asbestos” one day. The issues of micro plastics in our environment are disturbing as well.
All I really know is that it is uncomfortable to wear, and that it’s poor performance as a carpet, rug, and upholstery textile keeps me from recommending it.
To be fair though, polyester is probably ok if you don’t wear it, step on it, sit on it, or drink liquids that are contained by it or it’s by-products.