Suta Goswami said: “At the present time, the Kali-yuga has already passed its 3000 years. Now the king Sankha is ruling the earth and in the mleccha countries the king named Sakapat is ruling. Please hear about how they came up."
Now let's se this prophecy in Srimad Bhagwatamto have a clear picture .
Srimad Bhagwatam is popular for its authenticity as there are total 100+ commentaries on this Purana from 14th
So there is no question of Interpolation mad after coming of Muslims or britishers in Srimad Bhagwatam
This is the verse mentioning Britishers in Bhagwatam ( Bhagwata Puran )
Śrimad Bhagwatam 12.1.28
भूयो दश गुरुण्डाश्च मौला एकादशैव तु ॥ २८ ॥
Eight Yavanas will then take power, followed by fourteen Turuṣkas, ten Guruṇḍas and eleven kings of the Maula dynasty.
So clearly the Sages could see future and the prediction was fulfilled