The 2011 thing keeps getting cited in this thread, but it's wrong. The funding was cut because of what amounts to a booby-trap condition in pre-existing legislation. And they tried to get it overturned by it was blocked in congress.
In fact this is an almost perfectly partisan issue, and the 2011 canard is giving cover to some horrifying both-sidesism.
That pre-existing legislation (which banned US financing of any UN agency that grants membership to Palestine) was signed by George HW Bush in 1990 and expanded by Bill Clinton in 1994, in both cases passed by Democrat-controlled Houses and Senates. So it's still "both-sidesism," whatever that is.
And for what it's worth I never mentioned nor was thinking about "two sides," just multiple distinct administrations. Partisanship wearies me (and the parties have changed a lot over the last 20-30 years)
Under the Obama administration, the US stopped financing UNESCO in 2011(!) after it voted to include Palestine as a member state that year.
The Trump administration decided to withdraw fully from the agency in 2017.
The Biden administration rejoined UNESCO in 2023 and agreed to pay it $600 million(!) in back dues.
Now, the Trump administration is quitting it again.