The United Nations Relief and Works Agency is the principal humanitarian organisation operating in Gaza and the West Bank. In the immediate aftermath of the International Court of Justice hearing and its decision on 26 January, the Israeli government claimed that UNRWA staffers were helping Hamas. Without considering the evidence, a number of governments (principally the USA, Britain, Germany and France) cut all donations to UNRWA. Commendably, some governments kept or even increased their support (principally Norway, Belgium, Spain, Portugal).
The attack on UNRWA had been coming for some time and THIS ARTICLE from Jewish Currents sets out the history.
All countries except the US have since resumed their contributions to UNRWA (Britain was the last to resume). This is not least because the Israelis never released the evidence they claimed to have about UNRWA. The Israeli government has nonetheless passed a law banning UNRWA from operating in Israel (including East Jerusalem), that law to become effective in February 2025. The government of Norway is set to ask the UN to seek an advisory opinion from the International Court of Justice on whether the law can be allowed to stand.