Someone's pissy. Two main points of disagreement, let's start at objectively wrong. From wikipedia:

The term "tankie" was originally used by dissident Marxist–Leninists to describe members of the Communist Party of Great Britain (CPGB) who followed the party line of the Communist Party of the Soviet Union (CPSU). Specifically, it was used to distinguish party members who spoke out in defence of the Soviet use of tanks to suppress the Hungarian Revolution of 1956 and the 1968 Prague Spring, or who more broadly adhered to pro-Soviet positions.

So Tankie has never been about Tianenmen square, but it is the sort of lazy take one might land on when they don't have much curiosity about history and do their best to connect the dots high school gave them.

To the more misleading wrong:

They think that Ukraine is legitimately filled with Nazis in their government and military and that Russia is rescuing the poor populace from their oppressors.

Russia is not a communist country, and hasn't been in 30+ years, this is important to remember because too often people act as though Tankie's reverence for the USSR applies at all to Russia, it does not. Broadly the tankie take on Russia/Ukraine is that fundimentally NATO is a militaristic arm of western Neo-colonialism, and that after encroachment Russia started the war. Then during the Biden administration in particular, the US used this as a proxy war against Russia, and like with many of it's proxy wars, the US funded and armed politically radical groups. It is very much a view of there are no good guys in this war. I don't even really fully agree with this reading but again, my point was more that you don't really look into what your arguing and the laziness shows most notably in your guess about the history of the term tankie, and an apathy to even run spell check.