If you've ever registered on tsm boards change password NOW. 1300 unique username/email address with plaintext passwords on pastebin
Old version of forum software that never got updated and running an old version of php would be my guess. Website owners need to make sure things are kept up to date due to vulnerabilities.
I use haveibeenpwned.com Alerts me if my email address shows up..this one did with 1300+ others..I have reported it to pastebin, but it's out there now...
Old stuff was upgraded a while back and cleaned out but they may have gotten it before then. Not like there is any sensitive information there.
That maybe 95% hack proof but I prefer Paper and Pencil at 99% (i.e. 1% less due to natural disaster or misplacement).
Even if that was a three year old dump of data, it's most certainly sensitive data. People are generally very poor managing passwords.
The data was leaked around February 2018 and from what little I've read about it the actual breach was estimated to be from December 2017 so would certainly have been sensitive at the time when it first made it into the wild.