Power on virtual machine" is showing that DRS powered on the VM.System user.vSphere 8.x
vSphere 9.x
This is by design, the task will show the System user and will show DRS as powering on the VM if DRS is enabled on the cluster. The actual initiated user request can be seen when viewing Events and not Tasks.
View the event by browsing to Events instead of Tasks. Then look for the initiated event of "Virtual Machine is Starting" and this will show the user ID that initiated the power on task.