Banning + refund for the remainder credit, sure. Scummy, but sure. Shadow banning, taking peoples money while they still think they get a service, not even banning at the end of the billing cycle, without giving notice, nah, that’s definitely fraud.

It is if they silo you off without notifying you and make sure no one else can see you and keep taking your money. Now I don't know if tender is doing that provably, but that was the thesis.

It is if you keep taking their money and pretend that they are not banned.

Colloquially and technically "ban" and "shadowban" are different things; I have no idea what happened in OP case but "shadowban" means that you leave someone in a system but silently block all of their interactions.

e.g. ban: you try to log into HN and it gives you a message: "You can't log in, you are banned"

shadowban: you log in to HN with your account, you post comments and vote on stories but unknown to you nobody else on HN can see this. Eventually you start to wonder why you never get replies anymore.

It's definitely an ethical issue if you are doing the latter without telling someone, and additionally charging them for the service you aren't providing.

With a dating app it might be hard to tell for a while; how are you to know that you aren't getting any replies/engagement because of the way such sites work, or because the people you contacted never saw the likes/messages/whatever.