I’ve just read an article on a Russian poet, composer and performer Bulat Okudzhava and noticed that his last citizenship was named as поданный of the Russian Federation. It is very easy to google the article, and I won’t provide you with the link to it.
In Russian, поданный means subject not citizen. If in the linguistics in some ways we can use these terms interchangeably as synonyms leaving some stretch for interpretations, then from legal perspective their meanings are very different, therefore the editors of Wikipedia are supposed to know about this distinction.
A correct way to refer to his legal status with respect to Russia is гражданство.