I'm not sure since when, I just noticed today, all links I seen that have been typed at the end of a paragraph and then converted in links by the system have "</p>" at the end.
By that I meant links this one:
http://miezaru.donmai.us/help/ratings
adding a space after urls seems to be a workaround
http://miezaru.donmai.us/help/ratings
The url appears ok, but when I mouse over or click there is </p> at the end
Looks like the script that make the url clickable takes the next consecutive html tag inside the link, if there is no space before it.
Updated by albert