The data suggests some gamers are partially treating the service to trial or even rent a game they might be interested in, before unsubscribing.
This is me. I often subscribe when there's a discount, go through some games I'm not interested in buying but want to play anyways. Xbox game pass specifically has a lot of great indies that can be finished relatively quickly.
I subscribed earlier this year for a month, might resubscribe for a month again later this year.