Maxon One includes ZBrush as of April 20, 2022. The cost for Maxon One Individual and Teams Subscriptions will not change.
Maxon One subscribers will automatically see a new ZBrush entitlement in MyMaxon. Simply download the MyMaxon-enabled ZBrush installer from within Maxon App. ZBrush will automatically be licensed via Maxon App. Note that you'll need Maxon App 3.0 or greater.