Tankie's original use was for British communists who supported Soviet military expansion. In the modern sense, it is used to describe communists who are authoritarian-apologists. For example, a communist who romanticizes the Soviet Union or makes excuses for the Uyghur genocide is a tankie. I've also seen it stretched to include militant anti-capitalists, or more commonly, "militant," anti-capitalists who call for violent resistance to capitalism from the safety of a keyboard.
Democratic-Socialists are not tankies. Socialists are not tankies. I don't even think most communists qualify as tankies. Criticizing Democrats does not make you a tankie. Condemning Israel's human rights violations does not make you a tankie. Voting third party doesn't make you a tankie. I see this term used here every day, but never correctly.
Yeah, that's why I outlined how this term went from describing British communists who supported the Soviet's use of tanks during the Hungarian Revolution to generally pro-authoritarian communists to communists who call for violent resistance to capitalism (especially online). There's a difference between a word's meaning shifting over time and someone misusing or misunderstanding a word so badly they've lost its meaning.
Yeah, I don't think most people in this community would agree with the definition you just laid out, and as I said, this community is already misusing the word. What you're describing is closer to the, "dirtbag left," than anything else. You're stretching the definition so far past, "pro-authoritarian-left," that it's ridiculous. It would be like if I started calling Biden supporters, "Bernie Bros," and said the definition had shifted to include any supporter of a left-of-center male candidate. It's so incorrect it's made the word meaningless.