Budget: 11111 UAH Deadline: 15 days
Please pay attention to the breakdowns of source, medium. You may see in the dependencies of this data what exactly outputs the undefined source. In most cases, this is either direct (i.e., direct traffic), physical items like QR codes, or incorrectly set UTM parameters. According to the screenshot, I don't see that you have such large volumes of traffic that the analytics couldn't process everything, or you made a filter and that's why you had such a volume here.