I have no idea how it should work specifically but it seems there could be something like a hash to refer to ones account in public without disclosing your email address.

The internet is full of terrible experiences with companies. Even without much exposure someone working for the company might be curious what the hell is going on.

The implementation leaves much to be desired but the EU actually requires reviews from real customers. Or more specific, you cant publish a review if you cant prove it is from a real customer.

Maybe something like https://example.com/accounts/HASH and https://example.com/accounts/transaction/HASH

Then let the [banned] user pick which items from the account or transaction they want on public display.

Platforms can submit postings and reviews to the profile and the user can be prompted to confirm them and publish them in public if they want.

It seems a lot of overhead but bad reviews as a service is a thing and quite harmful.