White people in these countries are, on average, more educated and have better access to contraceptives and abortifacients. These countries also have strong women's rights and are currently going through shaky times where many are concerned about economy and the future (climate change). In America, especially, since the costs for birth and childcare are just incomprehensible.
This is result of a radical change in culture over the past 100 years from women being properly to fully-fledged humans who are allowed the same careers as men and the ability to say "no". Europe still had countries where raping your spouse was not a crime in the 90s.
On top of that, many men are becoming politically incompatible to women. Figureheads like Andrew Tate spread brain rot that men are owed relationships and encourage that they demonstrate the worst concepts of masculinity imaginable. So gen-z and onwards have a disproportionate number of women outright repulsed by the men on offer.
So white women are increasingly pursuing happiness through careers and friends and hobbies instead. They're not dating men they don't want. And they're not having kids until they feel ready and/or safe, if they ever want to.
Other minorities tend to be less educated, have worse access to required medical care, or still have social pressures being applied to them / differences in culture. So they have more children.
What would you do? Force them into marriages they don't want and impregnate them against their will? This is how freedom works.