So you’re not describing the issue where internet connected EV chargers can be easily hacked, and potentially told to dump the charge of the connected vehicle’s battery on the grid en masse, causing overloads and transformer explosions.
But a slow moving issue like that sounds like a frequency or voltage issue - something goes under or over enough and isn’t detected via monitoring, causing premature equipment degradation, and potential system collapse. Definitely a lot of expensive damage, though.
(Basically, a stuxnet-style attack on the utility grid - and we’ve already seen evidence that SCADA/PLC’s can be hacked in the water supply system.)
A destabilizing push, rather than a hit with a hammer.