Labour officials at the weekend told the Guardian that in opposition Labour had rejected the Conservative legal challenge to the ICC jurisdiction and its policy remained unchanged in government, but did not say if the claim was being withdrawn as a result.
I think globally a lot of parties moved to the right. Plus don’t underestimate the Israeli lobby in British politics. https://www.declassifieduk.org/israel-lobby-funded-a-third-of-conservative-mps/ and https://www.declassifieduk.org/labour-mps-have-accepted-over-280000-from-israel-lobby/