There's absolutely no reason to continue to support an organisation that doesn't even pretend to not be another country's lapdog. If China gets to have the kind of influence over the WHO that they have then they should at least be the ones who pays for it.
Secondly, there is a good reason to support the organization.
The problem being complained about is excessive deference to one member nation, China, as opposed to everywhere else. Defunding the organization will absolutely ensure this state of affairs continues, and in what ways they can act differently from China, they will no longer be able to do so because their sole source of funding will now be China, instead of one of many.
The solution isn't to defund them. The solution is to kick China out of it. That means China will not be able to fund the WHO, and the WHO will be able to operate without their influence, hence weakening China's ability to affect policy, and forcing the information sources on in-china effects to other sources, such as US intelligence and the FDA. It'd be a huge win.
The US defunding the WHO is a win for China, not a win for the US, because it entrenches a source of soft power, both in possibly manipulating data, and on providing support to poor countries to help build goodwill and prop up local dictators of choice.