Function CURRENCYH
Function CURRENCYH stopped working on Apr 26th 20231 - CURRENCYH("GBP","USD",0,"04/26/21") results in "The requested historical date is invalid or is in the future." I'm running Catalina 10.15.7
You can file a bug report with Apple via Numbers > Provide Numbers Feedback in your menu. There have been many complaints here about STOCK, STOCKH, CURRENCYH not retrieving data from Yahoo! Finance as expected.
SG