There's a Goodwill in my area where my wife regularly finds lululemon and patagonia stuff for cheap that looks like it was barely used if at all. Also cashmere sweaters, real fur coats and merino stuff for really cheap.
There's a salvation army a couple of miles from there that has severely used clothes a lot more expensive (and also salvation army 🤮)
There's also a "vintage" store that is super expensive and another that it's more like an exchange so clothes are good but expensive but you can also sell your clothes for credit
Do you have Android or iPhone? AFAIR the issue started because Google wanted to collect 30% of the sales
Edit: I wonder if free books don't have this issue, I got this book from the browser