LOL Kazakhstan might have different ideas there...
The grain thing is interesting, apparently, the current Russian claim is that the bridge thing was caused by explosives shipped out of Ukraine as a result of that corridor then shipped via some third-party countries - Armenia and Georgia into Russia.
The massive strikes thing is perhaps blatantly a lack of missiles, they simply can't sustain that sort of thing, several dozen fired in one evening is a huge depletion of their stockpile, according to this they have relatively few Iskanders left and the cruise missiles would quickly run out within a few days of them attempting to continue mass deep strikes like that. no wonder they've had to rely on things like anti-ship missiles or using S300s in ground attack mode etc.