Yes, looks like this change has been rolled out very recently.
Today I was not able to view channels that are not part of my DTH account subscription on xstream app though I have Airtel Mobile pack subscribed which gives all channels for free.
It is showing lock icon against channels that are not part of DTH plan and is playing 5minutes trail if we open with countdown of 5 minutes.
Edit: When on wifi, I am able to view only DTH subscribed channels, but when on Airtel mobile data able to view all channels. I have my Airtel number registered with DTH as well.
This is more like Tata Sky mobile app where only DTH subscribed channels can be viewed on mobile app but with an additional benefit for Airtel Thanks users to view all channels.