Hayat Tahrir al-Sham are on the Islamic terrorist list
There's no doubt they took advantage of Israel's pummelling of Hezbollah and killing Iranian military leaders in Syria. They saw an opportunity and pounced. Not sure if this was a CIA or Mossad plan though. These dudes are not exactly friendly to Western interests. But there are literally hundreds of rebel groups in Syria. Latest reports have rebel groups entering Damascus, but I think it is a different group from the southwest.