(Looking at the WHO's largest voluntary contributors [2], I could see the UK, Australia and France withdrawing soon, too.)
[1] https://www.kff.org/coronavirus-covid-19/fact-sheet/the-u-s-...
Unless they decide to step up their funding as a soft power play.
This is a better page for viewing the WHO's sources of funding, at least for 2022-23[0][1]. There are three separate categories of voluntary funding and only 6.6% of funds come from Core Voluntary Contributions as displayed in your graph.
Starmer is many things wrong but one thing he won't do is renegade on international treaties and agreements.
You're right, I brainfarted and mixed up the coming political shifts in Canada and the UK.
The WHO being outside politics is good, it means it can focus on health/science and not worry about appealing to electorates.
I think Trump has a point though regarding China's contributions, China isn't a poor country but the WHO doesn't really have any way of forcing it to pay more.