The general usage refers to people who are so brainwashed that they will ardently deny and even defend massive crimes against humanity committed by their government. In the case of China, deniers of Tienanmen or the Uyghur Genocide would apply. In the case of America anyone that denies israel is committing Genocide applies.
And the glorious leader supporting that Genocide is none other than Genocide Joe Biden.
Calling someone a tankie is saying "You're a piece of shit not only because you support these atrocities, but you dare call yourself a communist while doing so."
I think the term does not mean what it meant a long time ago as even the Wikipedia article states that there's already like 7 definitions of it. The original definition is not even related to the Tank Man which is its most popular reference these days.
After the Prague Spring, the term was used to describe Communist party members of Western countries who had supported the invasion of Czechoslovakia
I see no reason to for the arbitrary limitation to only call Communists Tankies as we could also start a semantics discussion that China and Russia aren't exactly communist countries anymore.