See the documentation here: https://docs.mendix.com/refguide/task-queue#context
Look at the 2.7 part:
2.7 Execution Context Prior to Mendix 9.6 tasks were always executed in a sudo context, even if the scheduling microflow had Apply entity access set to true (see Microflow Properties for more information). As of Mendix 9.6 this behavior has been deprecated and tasks now run in an equivalent context to the one in which they were scheduled. This has the following effect: When a user is logged in, the task will be executed in a new context for the same named user. This context will be the same as if the user is logged in. When no user is logged in, the task will be executed in a new anonymous context. This context will be for a new anonymous user with the same language and timezone as the original user. When a system session is used to schedule the task (using the Java API), the task will be executed in a new system context.
This means that you do know now what user it is. Because you now have a currentuser object to use.