I recall last time that the percentage of answers an user has accepted as the right answer was displayed under the username.
However, recently it seems to have disappeared.
Is that true?
Yes, it has been removed. See this MSO answer. The reason given there is, I quote from the question:
We generally seem to agree that harassing a user about it is not appropriate and that our decision to answer a question should not depend on it, yet we display it in varying terrorist-threat-levels of color. Yes dear users, please don't pay any attention to the brightly orange colored percentage you see there. And whatever you do, don't bring it up.
But as long as you're displaying the accept rate, people will comment on it, criticize users for it and possibly reconsider answering because of it. And while I'm of the opinion that a low accept rate should not stop you from answering (we're here to make the internet better after all) and that the possible reputation gain (or lack thereof) should not factor in either, I can't blame users for considering it. It's in their face after all. And we're only people.
Not everyone agrees with it (hard to please the crowd, eh?). See Replace accept rate with citizenship level.