This is something I always get in arguments about, whenever I use the word tankie hexbear and grad users argue that its just a term for socialists.
I’ve always just used it to referr to authoritarian communists, i.e, people who unironically support modern russia, and/or oppose ukraine, and think nothing happened to the uyghurs.
“No true Scotsman” is about redefining a term to suit the argument, not that purity tests or gatekeeping are inherently illegitimate.