The most decisive factor is Saudi Arabia and the impetus for Saudi Arabia to make important strategic adjustments for the future of politics, security, stability and intra-regional cooperation is the reduction of the US while China and Russia increased their interest and direct involvement in cooperation with countries in the region.
There is a matter of national interest here. Saudi Arabia realizes that it must adjust its strategy before it is too late. Without normalizing diplomatic relations with Iran, the war in Yemen will not end anytime soon. Meanwhile, another war has cast a shadow over the region that has broken out in Sudan, where Saudi Arabia wants to play a role as a mediator and end the civil war, rather than directly wage war. Reconciliation with Syria helps Saudi Arabia not push Syria further towards Iran, Turkey and Russia, while already a number of countries in the region gradually normalize relations with Syria.
Saudi Arabia initiated the initiative, so it must also take the lead in ending the diplomatic rivalry with Qatar - joined by Egypt and some members of the Gulf Cooperation Council. Saudi Arabia has publicly shown that it is no longer the most pro-US support for the US as it has been for a long time, and at the same time is very friendly and enlists China.
Establishing a key decisive role helps Saudi Arabia gradually become the true center of power in this great region.