I assume all chat logs are used for training in one way or another because it would be foolish to not do that.
On the other hand, having it leak that you train on your customers data, ignoring the opt-out, is probably existential when close alternatives exist in the market.
There is no AI, all these companies have is the chat logs so unless you have further evidence on what they do or don't do behind the scenes I recommend you use a more conservative approach in your assumptions about what they use or don't use for training.