Many who are classified as "Hispanic" are whites of mostly European heritage.
And not all who are classified as "white" are European. The government classifies all Middle Easterners (Arabs, Israelis, Persians) as white. Although all those groups are increasingly self-identifying away from "whiteness" to avoid the stigma.
Indians used to be classified as white by the Census, until a few decades ago, when Indians realized there were benefits to being classified a racial minority. They successfully lobbied to reclassify themselves.
Finally, these classifications are self-reported. In the past, mixed race people preferred to be regarded as white (because that came with more societal benefits). But lately, mixed race people prefer to be regarded as non-white (because of all the societal benefits).
So some of the decrease in white population might simply be people on the edge reclassifying themselves from white to nonwhite.
The decrease in the White population is from decades of harangues from far Left genocidists like Paul Ehrlich rasping about “overpopulation”, the selling of abortion to women who were told to become wage workers instead of mothers, and outright discrimination in the form of “affirmative action” for africans, mexicans, indians (dot, not feather) and of course all of asia, which is hilariously termed a “minority” when there are like 4+ billion of them.
Genocide against Whites and especially White Protestants - the people who founded the US - is the goal.