The term originated from those who followed the party line of the Soviet Union. Specifically, those who supported the use of tanks to quell the 1956 Hungarian Revolution were the original tankies. Today, it is used by liberals in the same way that a boomer would call Democrats “commies”.
It is typically used as an insult by liberals who believe that they are the most progressive people on the planet. Instead of facing the harsh realities that they support fascist and imperialist policies or that someone else might be to the left of them politically, they instead berate anyone who calls them out on it.
If you don’t support NATO, you’re a tankie. If you have anything good to say about China, you’re a tankie. If you don’t think France should invade Niger - tankie. If you oppose sending tanks to Ukraine - TANKIE.
