I just looked this up. It is currently available to limited sellers on an invitation only basis. They say they want the majority of sellers on managed payments by 2021. It is NOT a current requirement and I don’t know if it ever will be. If you are a high volume seller it might make sense as you will save a small percentage of fees. I don’t plan on signing up for this at all.
Done selling on eBay, they are demanding my social security number to sell
They are forcing everyone into what they call "Managed payments" that requires you to give them bank account information and your social security number. Looks like I'll be selling here from now on. I know I gave it to PayPal years ago so they have it, but I'm done giving it out. I called and the rep told me they are legally required to have it in order for me to sell. That is a load of crap.