Although I agree with you on subscriptions in general, it is not quite as easy as blocking just one site. There are more popular remote desktop software than a regular person could list easily.
But maybe the good news is, that if blocking is enough for you, that’s in the free version, right?
The corporations have their own contracts with e.g. Microsoft/OpenAI. The data will likely be sent the same way as with the public tools, but the providers promise not to use it for other purposes.