You have an Azure AD tenant named adatum.

According to the Microsoft documentation, when you assign a license to a group, all members of that group are automatically assigned the license. However, if a user is already assigned the same license directly or through another group, the license is not duplicated.

In your scenario, you assigned the Azure AD Premium P2 license to Group1 and User4. This means that all members of Group1, which are User1 and User2, will also get the license. User4 will get the license directly.

User3 will not get the license because they are not a member of Group1 or assigned the license directly.

Therefore, the users who are assigned the Azure AD Premium P2 license are User1, User2, and User4 only.