The DM was a DM asking us to change our no tankies policy and remove the fuck tankies banner as it was apparently upsetting hexbear users. Apparently tankies view the word tankie as a form of slur. The admin wants us to ally as a form of "left solidarity"
I totally agree with your definition here, but I'd add there are some on the right who use this term to describe and dismiss almost anyone on the left. The right consistently wages war on language, co-opting words with existing definitions and changing them to suit their agenda. "Woke" is one example of this, as is "critical race theory."
I don't think I've ever seen a mainstream right wing talking head say "tankie" and frankly I'd be impressed if they even admitted they knew the difference between the various factions of the left instead of grouping them all together. Seriously, "liberal" and "Marxist" are completely interchangeable in right rhetoric.