Let's imagine that a political opposition leader from Russia were to take refuge in the US. Now imagine that Russia performed a "surgical strike" bombing in the US to kill what they viewed as a terrorist leader. Can you imagine the outrage that would occur? That's exactly the situation that Qatar has just experienced.
It's an act of war. One country bombing another country means they are at war.
Now, the power dynamics in this region mean that they'll probably get away with it, and Qatar is more likely to let it slip than not, but it's still morally reprehensible.
No, that's not the point. Whether someone is a terrorist is subjective. Russia could (and likely would) define their opposition leader as a terrorist.
My point is that if Russia were to conduct a bombing on US soil, regardless of who it was targeting, the response would be severe and the reasonable onlookers would not blame the US for being "upset" about it. Yet that is exactly what Israel has done to Qatar.
There is in fact international consensus on what constitutes a terrorist organization. Hamas, ISIS, Al-Qaida, Hezbollah, Houtis, Boko Haram and so on, very clearly quality.
Sure, China or Russia can and will label political opponents "terrorists" to justify persecution against them. Their goal is to destroy the international consensus, so that "terrorist" becomes a purely subjective label. By equating Israel's bombing of an actual terrorist group with Russia's persecution of a fake one, you are supporting Russia in this effort.
Instead, you should equate Israel killing Hamas leaders with the US killing Bin Laden, coalition forces bombing ISIS in Iraq, France bombing islamists in Mali, etc.
"Terrorist" is just this century's n-word. It has been applied wilfully by racists towards their chosen out-group victims in order to justify their atrocities.
It's an act of war. One country bombing another country means they are at war.
Now, the power dynamics in this region mean that they'll probably get away with it, and Qatar is more likely to let it slip than not, but it's still morally reprehensible.