You are kinda on the right track. The filesystem is a map of the "metadata" of a file, including where it is actually located physically on the drive. If you repartition (or quick format) a drive, you are removing the metadata about the files, not the actual files themselves. If you physically scan each sector of the drive you will find common file headers that will identify the rest of the file. With videos this can have corrupted bits of data, with images less likely, documents are very very easy to recover. So you can have a 256GB drive, that might have 40GB of spare space, but sector by sector scans can find metadata of previous files (or partitions) and that can go back several times, each time different bits of data being recovered using for lack of a better explanation "math". Anyone that has done data recovery on spinning disks has been watching this whole part of the story in disgust. You absolutely can recover more data that the whole of a drive, going back several "partitions". Remember kids, write zeros, multiple times. Pref write ones then zeros, multiple times.
Further, I recall that the number was provided with the qualifier that it was not de-duped. Meaning that hunter could have formatted, synced his cloud bullshit, then formatted, then synced his cloud bullshit, there might be multiple copies of the same files across different partitions located in different physical sectors of disk. Again this is very common to anyone that has done data recovery, the more you find in 1 partition, the easier it is to find it again on a previous partition.
Furtherer, pretty sure nobody has measured or claimed to have measured how much bullshit is in the cloud, if you have more storage available you could just sync more shit. There are so many loopholes in this debate to absolutely make it possible to recover more data than total physical storage.
>If you are certain this is true. Please speak out more, and loudly. People need to know this.
I have first hand experience that confirms I am certain that this is absolutely true. If there was ever a file system and not always raw, then it is possible. One would only be limited by their skills, techniques, and equipment. As always do not want to get into a technical dick measuring contest online, especially here. Those who know, know, those who want to know will find out. This might be a niche skillset but it is easy to understand, just search videos on data recovery techniques, then extrapolate.