I strongly suspect what you saw in this paper was Samsung's[1] auto-trim (people often use inaccurate terms like "idle garbage collection") that reads the NTFS allocation bitmap and trims free space, a feature that was only included on a few SSDs because it is a potentially unsafe rampant layering violation. In the history of SSDs, almost none have auto-trim, so the results from this paper are highly non-representative of SSDs in general.
[1] Note that the Corsair SSD used in this paper is rebranded from Samsung.
"I strongly suspect what you saw in this paper was Samsung's[1] auto-trim "
Yes, that was the reason for picking that drive (the research budget for the project was a mere $500!), since I was pretty confident the effect might show up from it.
However, it was a lucky guess that it would show up in the presence of a write blocker and in the time frame of a forensic investigation (normally the first thing that happens is they quickly copy the disk), since those are unusual constraints.
I think I prefer to call the technology the same as the manufacturer's name: idle garbage collection - since TRIM has a clear meaning in this context, and the drive is not automatically generating TRIM commands and it doesn't behave exactly as though the O/S had issued them either (e.g. most but not all gets wiped). Hope we can agree to disagree on that one!
[1] Note that the Corsair SSD used in this paper is rebranded from Samsung.