I think I already know the answer, but I'll ask out of sheer curiosity.
After recently switching to Opera, it appears that I already have an Opera Link account. The best I can guess is that it's associated with an old MyOpera account that no longer exists. I do not remember signing up, but my username is so uncommon (ehlodex) that I have a hard time believing that another Opera user chose the same one.
Is is possible to recover an Opera Link account without the registered email?
(edited for readability)