@Naamah Ninio, Thanks for posting in Q&A. In general, for configuration profile assign, we use device groups when you don't care who's signed in on the device, or if anyone signs in. You want your settings to always be on the device. We use user groups when you want your settings and rules to always go with the user, whatever device they use.
For your situation, it seems you have assigned to device group. So the system account also shows applying the policy. To avoid this, you can assign the configuration policy to user group instead to see if the result will be different.
Hope the above information can help.
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