Likely the HTS, which is the main rebel group that lead the new offensive and which has already absorbed or eliminated many other groups in Syria.
They are a Sunni Islamist group, but they also are against Al-Queda. But only opposed to them since 2020. But HTS is still considered a terrorist organization by the US, UK, and Canada. But Timber Sycamore shows historically that the US may publicly designate a group as terrorists in Syria while style still supporting them privately. HTS is strongly opposed to Russia and has spilled a lot of blood to prove it.
So, in short, is this a good or bad event: I dunno.
He seems like he follows whatever gives him the best position. Projecting moderation to the west is a no-brainer, but he also has to contend with projecting the correct stance to the groups inside Syria and that is likely going to be a much less moderate one.
There is also the outside factors of Russia, Iran, and the US. There are a lot of considerations for all of them and I won't even pretend to predict how they will all act and react, but I do want acknowledge they can and likely will all drastically affect Syria.