Even if you disagree with them, Trotskyists are not tankies, simple Marxists aren't tankies, leftists curious and exploring different theories aren't tankies, and ffs anarchists like myself are not tankies.
I feel like "tankie" indicated a very specific worldview at one time, but it's been used lately a lot to mean things like "doesn't agree with nations supporting oppression and inequity up to and including genocide" -- which is drastically at odds with how I've seen the term used in the past, no?
The way I've heard "tankie" defined is blind defense of anyone waving a red flag, no matter what they do. I do think there might be a very limited use-case for that because you do occasionally get like edgy teens like that, but I'd argue that it doesn't apply even to all - or even most - Marxist-Leninists.
If the USSR was so perfect, then why did it collapse? How is it possible to reconcile blind defense of Stalin with blind defense of Kruschev, who hated Stalin? Or Deng who criticized Mao, or the whole Sino-Soviet split, and so on. Even if you tried to, you couldn't really blindly defend everyone calling themselves a communist because there have been too many disagreements and failures.
It would be pretty easy to trip someone up if they were really just blindly defending anyone who calls themselves a communist, but the people accusing people of being tankies never do. If anything, they seem to strongly resist any sort of nuanced discussion of the successes and failures of self-described socialist projects. I'm sure there's someone out there who would call you a tankie if for example you acknowledged that Cuba's literacy program was successful and a good thing, regardless of anything else you think about Cuba. It really seems like it's less about "blindly defending," and more about "not blindly condemning."