Labour has had a bit of a dilemma. It has had a strong reachout to UK Muslim communities (among others), and encouraged muslim minorities from joining the Party. It has also strongly aligned itself with the Palestinian cause.
Unfortunately, these minorities - and the Palestinian cause - have a strong anti-Jewish element arising from their Scriptures, and from UK mosques heavily influenced by the Salafi school of Islam, strongly promoted by Saudi Arabia Wahhabism. These attitudes where inculcated into the Labour Party by the new membership, and by MP's trying to curry favour with those communities.
The Party has done a lot of work in recent years to reduce anti-semitism. I don't particularly like Labour, but under Kier Starmer I don't really think this is really a problem anymore ?