To understand all the 'whys, hows, and whens', that would take some.
https://www.helion.co.uk/military-history-books/moscows-game-of-poker-russian-military-intervention-in-syria-2015-2017.php?sid=3aeef9c9c9f4b…
To understand all the 'whys, hows, and whens', that would take some. For the start, you would need this one to understand the 'basics' of relations between Putin, Assad, and the IRGC in Syria:
https://www.helion.co.uk/military-history-books/moscows-game-of-poker-russian-military-intervention-in-syria-2015-2017.php?sid=3aeef9c9c9f4bbacb90e278c27d1ba7c....and then much more to understand developments ever since 2017.
Very, very compressed, and tactically, the following is important: all Russian bases (and thus all their air defences) are concentrated within the triangle Sanobar-Masyaf-Tartous. The purpose of Russian air defences in Syria is the defence of Russian bases - and nothing else. They are not there to protect Assad, and even less so the IRGC.
Means: as long as nobody is targeting the Russians, they are not shooting back.
...while the Israelis are exclusively targeting the IRGC.
Unsurprisingly, Israeli 'problem' are not the Russian air bases (or Russian air defences), but the fact that ever since the series of most fierce Israeli air strikes on the IRGC in the country, run back in 2017, the IRGC moved its most important facilities precisely within that triangle, especially to the Masyaf area.
With other words: the IRGC 'found protection' through 'hugging' Russian bases in Syria.
(This is how comes that the Assadists then shot down one of Russian Il-20s off Syira, back in 2018: the Israelis attacked 'over' and from the direction of that Russian aircraft, and in direction of Mayaf - and the Assadsits 'returned' fire.)
Finally, even after the lastest Israeli air strikes, all that has happened was not that the Russians have opened fire, but that the Russians have granted permission for Assadsits to fire back with their S-300s. Even then, these are granted to open fire only if the Russian HQ at Hmeymim says so - because the VKS is refusing to share its IFF with Assadists.
Thus, and I'll repeat for emphasis; Russians in Syria are no problem for Israel. But, the fact that Israel hopes Putin might curb the IRGC build-up in Syria - that is the daydream I'm talking about.
The reason: as long as the IRGC doesn't touch Bashar al-Assad, Putin does not care about them in Syria. The IRGC learned that lesson in early 2017, when its coup against Bahsar was spoiled by the Russian troops. Ever since, it gave up that plot and is instead building-up its para-state in the country: Tehran is, officially, considering Syria its 32nd Province, and its clergly is working activelly on converting as much of the population to the Shi'a sect of Islam. ....and Bashar can't do anything about this, becuase he's got no money: since 2011, he's all the time financed by Tehran.
Again, all of this - including reasons, evidence etc. - is explained in the book linked above.