This is not the usual spelling in any of the Scandinavian languages (in Sweden and Denmark it is Freja and in Norway it is Frøja) but it is the common spelling of the goddess's name in English. In the 2000s it became popular in Britain.
In the United States this form was much less common than Isabel until the early 1990s, when it began rapidly rising in popularity. It reached a peak in 2009 and 2010, when it was the most popular name for girls in America, an astounding rise over only 20 years.
A famous bearer is the Italian actress Isabella Rossellini (1952-).