In terms of the "tankie problem", it's mostly supporting Russian aggression in Ukraine pretty much solely to "own the libs" and "get back at the evil NATO". Most "tankies", a term that has become effectively meaningless from overuse, are more accurately political contrarians who care less about things getting better for more people and more about Owning The Libs.
There's honestly a good chunk of them on most fediverse instances just due to the general community vibe, with Hexbear having more than, say, lemmy.world, but less than lemmygrad. Hexbear stands out moreso to being the successor to Chapo Trap House, a community notorious for being so utterly vile to interact with that nobody wants anything to do with them.