I just want to be informed, how does that work? How can it be recovered if I wipe every single byte off my drive? This isn't windows where they have restore points or some shit
Let's start with unencrypted media...
For hard drives: sectors are written, rewritten and eventually go "bad". Some sectors that go "bad" are replaced with nearby sectors. The old data on those "bad" sectors is not erased, because there is no longer a logical block address (LBA) associated with that physical block address. For nation states / universities, even data that was overwritten can be recovered using a magnetic force microscope or other techniques that perform statistical analysis on trace magnetic remnants.
For Single-Level Cell (SLC) SSDs, things are much worse. Flash media is not really like a hard drive. Lots of folk may tell you about the read/write/erase size disparity... but it's easy to understand that an overwritten sector is not actually erased for a (potentially long) time. Less known factors also can make it easier to recover data. For example, the more power applied to cell during a write, the more destructive the write is to that cell (but it will hold the data for a longer time). Thus, the first time a cell is erased, it's actually quite easy to see the data that it had contained prior to erasure (where easy is defined as using powerful microscopes and custom software to parse the results). Even after writing the cell again, given that you now know the value stored, you can determine the prior values stored. ((In fact, this is similar at some level to how MLC SSDs work.))
For encrypted media, it's essentially the same as the above, except that you also need to know the keys used to encrypt the data. Sadly, some early implementations simply used a few flash cells to store the key, treated those cells as SLC media (even on MLC drives), and thus due to the destructive power on those cells, it was once again easy to extract the keys, so long as the key wasn't changed many times.
So, encryption is useful, but relies on complicated systems that have to deal with physical materials that rarely (if ever) act in a binary way. As a result, some information can often be recovered, and this is only based on publicly known techniques...