Putin as well as Iran gave up Assad, not because they wanted to they had to Russia's war in Ukraine is not going well without the former Wagner Group who were also their enforcers in Syria and Africa. African dictators are now also worried and may go back to the West.
True, the writing was on the wall that Assad's government was not salvageable and gave up their friend Assad 1. though Putin already had other resources stationed in Syria 2. as for Iran, after the Israeli strikes, they may have little to no resources left 3. also they would have to fight not just HTS but perhaps Turkey as well
It appears, Putin was already cultivating new relationships in the region and to have done the unthinkable striking a deal with his friend Assad's enemy
Iran and Lebanon, both backers of Assad, were also fighting battles of their own, with Israel's relentless decimation of their strongest rebel force, Hezbollah, in recent months
