Ukraine gaining approximate artillery parity, depletion of Russian armor and Ukrainian deep strike efforts becomingly increasingly devastating to Russian logistics as Russian air defenses/radar are obliterated leaving gaping holes into fragile parts of Russia's war machine in the wake of their destruction (Russia is failing to replace destroyed radar, they don't have the production nor maintenence capability too). The point I identify was somewhere in late summer when it became clear the Russian summer offensive was failing to do anything but take tiny amounts of territory in exchange for shocking losses.

Further Russia is transitioning to indiscriminate flying bomb attacks on civilians which is itself a blatant sign Russia feels it looks too weak on the actual battlefield to project strength and inevitability.