OS packagers have bugs like this every so often, because they still run custom upgrade scripts behind the scenes. Pretty sure I remember one in Debian a few years back (sorry, name escapes), and it was not the first time I remember seeing that.
I have only lost data due to hard drive failure, or at my own request (i.e formatting over what I thought I had backed up).
I recently enabled TRIM on my full-disk-encrypted SSD system. No sign of data loss yet.
I have always used ext3/ext4.