Will having milk tea more than three times in a day cause darkening of the skin.
This seems to be a common misconception and there are many non-peer-reviewed articles online debunking this myth; like this example.
In a review of literature, Tea and Health: Studies in Humans, Khan and Mukhtar report the evidence for various health effects of tea, and hyperpigmentation (darkening of the skin) is not among them.
I cannot find any evidence of tea or milk causing darkening of the skin.
In fact, extracts from some tea seem to have an effect on reducing melanin production in vitro. In this paper, Anti-melanogenic effects of black, green, and white tea extracts on immortalized melanocytes, Camellia sinensis water extracts reduced melanin production. It is important to note that this is a laboratory study and I could not find any evidence that drinking tea has any effect on skin pigmentation.