Starbucks isn’t special here, it’s a waterproof cup. I always assumed it was some kind of wax too so I also had a flashback to all the paper cups I threw in a recycling can [0]. But on second thought, what kind of wax deals well with water at 95C ? They’re all plastic coated.

[0] I guess most recycling is land filled or dumped in the ocean anyway, so my sins didn’t affect much of the outcome