Israeli landgrab in Syria.
They announced a "buffer zone" to be created within Syria. Funny because the Golan Heights is Syria.
Jewish expansion has two modus operandi:
1. Jewish settlers move into an area, this generates clashes with the natives who don't like this at all, Israel then has to guarantee the security of her own citizens, so IDF moves in to "keep the peace";
2. IDF occupies a piece of land as the aftermath of some local war, soon Jewish settlers follow, and establish colonies.
You can bet your ass that after this "buffer zone" is established that #2 will happen.

This also confirms that the Israeli leadership knew that something will start in Syria when they made Biden to put forward the accepted Biden's cease fire proposal. And they calculated with the possibility of fall of Assad's regime, or at least with a situation where the IDF can march into Syria.
But I'm going that far that they had a serious groundwork to create that situation. Perhaps even stretching the Gaza conflict this far, and the incursion into Lebanon was a tool to prepare the IDF for an invasion against Syria. Wars start with war games, so the troops have a muscle memory of what to do. Gaza and Lebanon was a war game for the IDF.

I don't think the rebel forces (HTS and SNA) are close enough to do anything about it. I think Israel infiltrated the SAA, and they prepared a coup against Assad, chiefly by paralyzing the SAA. They reignited the resistance in south Syria as well. The rebel forces just had to hurry forward with some units.
Besides the whole Syrian rebel forces is just some thousand people. 10-20 max. How large is the IDF after the mobilization? 500K? 1 million?