This was years ago. I dont remember exactly when but it was a handful of years ago. Pretty sure this was from before they migrated hosting even.
And I remembered that I also used that PW over at diyaudio.com so my bad. I can't actually prove which forum it was but it was from one of the two.
I have a monitoring service and i will get a notification "Your information has been discovered on the dark web" and it wont reveal the whole password, only the first character and last character. All it takes is just those two chars for me to pretty much tell. So i tried it on haveibeenpwned, sure enough its been in one of those combolists.
This was purely based on the password (I use a password manager and theyre all random now). I only ever had one email and that was involved in multiple breaches. That email eventually died off and I have a different one now. That was an ISP email.