Game Pass Ultimate is limited to just 15 hours per month.
A screenshot showing hours remaining of Cloud gaming for XBOX Game Pass subscribers.

XBOX is about to place some laughably bad time restrictions on cloud gaming for Game Pass subscribers. Starting in November, players will get, at most, just 15 hours per month of cloud gaming access, and that is only for Game Pass Ultimate subscribers.

Those with lesser subscription tiers will get even less time to game on the cloud. Game Pass Premium subs will get just 10 hours per month, and Game Pass Essential subs are limited to just 5 hours of cloud gaming per month.

Currently, there are no restrictions on the number of hours per month that Game Pass subscribers can spend gaming through the cloud. Subscribers will be able to continue playing their games through the cloud until the time limits go into effect in November.

Microsoft claims that they expect the change to only impact 4% of all Game Pass subscribers. It sure comes across as a particularly big "fuck you" to those 4% then.

If an individual utilizes all of their allocated play hours for the month and wishes to continue gaming, they will be required to purchase additional cloud playtime through the Xbox Store. Although specific pricing information has yet to be disclosed, Microsoft has stated that "available hours, purchasing options, and cloud gaming features may vary by market." Further details regarding pricing and additional information will be communicated to the public prior to November.

The reason provided for this change by XBOX is the most obvious one: Money.

We’re introducing this model because the cost of providing cloud gaming grows as more people use it and play for longer. Moving to monthly limits allows us to keep offering the service while continuing to invest in its reliability and performance. We understand that for some players the practical result is a higher cost.
Also in November, XBOX players will be able to purchase cloud playtime hours through the XBOX Store without a Game Pass subscription. XBOX says that this will "provide another option for people who want occasional access to cloud gaming or do not want a recurring Game Pass subscription."