Complex sentence: The trend has been very different in Quebec, however, where in the 1970s English lost its status of full equality with French, which is now both the "de facto" and "de jure" sole official language of Quebec.
Split into simpler sentences: The trend has been very different in Quebec, however, where in the 1970s English lost its status of full equality. Today, French is, both "de facto" and "de jure", the sole official language of Quebec.