This can happen when TRIM is disabled

Here's a study published last year I read that goes through this exact thing

In consideration of results obtained from the experiments, it concluded that the behavior of Wear Leveling in different SSD manufacturers having the same storage capacities does not match. It varies based on the number of files, types of files, and sizes. The recovery of files from different SSD manufacturers showed different results. In all SSDs, not a single trace of any file found in disk format scenario(s). Whereas, some of the data recovered in the delete case and from only one drive. It clearly showed different behavior of data recoveries in format and delete cases. The obvious finding from this study is that the time interval of image acquisitions played a significant role, and the longer time interval supports few chances of data recovery because the TRIM and Garbage Collection process effects clearing residual data from the drives

Non PDF link

Edit: corrected links