Good question.

98% of the 13022 people polled said Markle had an unfavorable impact on the Royal family. That equals around 2% of the sample size... not 2% of the British population.

If you had the selection criteria and the standard deviation estimate, you could use that just as political polls do to get the number you are asking about.

Regarding my second estimate. The 90% of POCs who felt that way, I did preference that with the phrase "assuming it was a legitimate poll", since I don't know how the "sample" was selected.

But if it was a legitimate statistical poll of the British people, since because 20% of Brits are POCs. The poll should have included around 2600 POCs. And if every person who favored Markle was a POC (highly unlikely) less than 10% would have viewed her impact as favorable to the British royal family.

Interestingly, people view Markle's impact with respect to the Royal family different then they view her. While 98% viewed her impact to the Royal family as negative, 23% of people polled through YouGov viewed her favaorably.

This polling organization is internet based and skews toward a younger population. And the question is different... the first is how they view Markle's impact on the Royal family and the second is how they view Markle herself. Both come out overwhelmingly negative.

It would be interesting to delve further into why the British people view Markle negatively. I can think of several reasons and skin color is not high on that list given they have elected POCs to by mayor of London and Prime Minister.