Same situation, life time account that I got like 10 years ago.
I didn't play for a while, 4 years ago I tried to log in and it wouldn't work.
My account seem to still exist because I can reset the password for it, but after password reset, I am unable login with the credentials that I just set.

I feel like they got an opportunity to get rid of some lifetime account that don't bring in anymore money and booted us out.
If that's not it then I would be curious to have their take on it.
Doesn't look like they are willing to answer here either.