Yes, I've heard this news, and this happened just moments after Trump was inaugurated as US president. What I know is that Trump made this decision because he was disappointed with the WHO, which he considered failing to tackle the Covid pandemic. This withdrawal of support will probably have an impact on world health management because the US is the largest donor to WHO (hopefully not). Will African countries get other donors? maybe, but it won't be as big as the US.
Its really huge loss for WHO for US to take out their support on their organization but they still have large donors which provably could sustain their operation even if USA is not on their side anymore.
See this list of their top donors here
https://www.statista.com/statistics/1456464/largest-donors-who/But with this actions they made provably there's lots of people will get affected on their decisions. But let see if WHO would do more better that can impressed Trump since maybe they are just giving them a lesson and provably will return their humanitarian support if there's great changes happen.