Is there any example in the world where there are more and more immigrants in any country or big city, which leads to the mainstream language becoming an immigrant language?

In today's world, except Britain, all countries speak English, such as the United States, Canada, Australia and India (the official language of India is English, but Hindi is still used by the people).

There are also some African countries and American countries. English and French are the mainstream languages and have become immigrant languages. It should be noted that although these are caused by colonialism, they are still immigrants.

Add an example of a city-Quebec, Canada speaks French and was originally a French colony. In fact, Hong Kong is the same, only better. Chinese and English have similar status.