In Israel, “Let off Steam” means allowing the colonial thugs continue their bullying of the native Palestinians.

You know, that land that's been occupied since 1967, and a brutal apartheid rule has been in place since.

Another term to describe this kind of right-wing brutality is slow-motion genocide.

https://consortiumnews.com/2021/10/08/report-spike-in-israeli-settler-violence-against-palestinians/

Settlers motivated by Zionist colonial projects call the Palestinians “encroachers” and attack them to expand the Israeli settlements causing further displacement of Palestinians. Members of settler groups like Hilltop Boys and Price Tag have even been prosecuted in some cases of murder of Palestinians.  

Though the settlements are illegal, successive Israeli governments have provided them full security. The country has recently started following a policy of minimum interference during the violent attacks on Palestinians.

According to the Haaretz report, the security forces called it a “Let off Steam” policy to create a “permissive atmosphere” to minimize their confrontation with the settlers.