You said they are close source, how can we know that they are not having their users seed phrases?
We don't know, but this is not the issue in this case, and nobody that I know reported stolen seed phrases by using Exodus wallet.
There is a chance OP would get the same issue even without exodus wallet, if same partner exchange was used.
Closed source should be avoided for different reasons.
They require video verification. A statement of payment documents. My passport and account information.
But I don't need them! I don't need that kind of exchange. I just asked them to return my ETH and cancel the exchange.
Many centralized exchanges can ask the same thing when you use them directly.
Only eXch is never asking for anything like that from their customers, or you can use decentralized exchanges instead.