AMA: Windows Security

I have been looking at Microsoft Defender Security Center lately and have a question about device groups. I have a freshly created tenant with no groups set up by default. Now when I create my first group "Device Group1", I get the group "Ungrouped Devices (Default)" in addition to the group I created. By itself, I understand that it makes sense to have a default group that contains all devices that do not belong to my device group. The question I have now is the following: In the default group the Remediation Level is set to Full, but what if I don't create a custom group and I can't see any groups on my dashboard (see first image). Are all clients already in the default group by default before the first manual creation of a group and the Remediation level is also set to Full there or do the devices all have no assignment before?