Why does this matter? China gets more than 50% discount on LNG imports from Russia is a massive sign of Russian desperation and China putting the screws to them.
Russia isn’t doing this because they really like China. This shows they have no leverage or options at this point. The big picture of money coming in for Russia greatly affects their warfighting capability. This type of agreement is worth paying attention to.
You’re absolutely right, Russia is a vassal state to China. Or worse, they might now be a resource colony to solve any problem that china has with minerals, energy, fresh water, capital markets, etc.
India is currently run by emboldened Hindu nationalists and they always like being on the good end of an economic agreement, let’s say. They have a long history of close relations with Russia, straddling the middle ground as a founding member of the Non-Aligned moement. China likes China, and ONLY China. If your interests intersect for a while, that’s nice - but not the point.