If we look at how things went for Mastodon during the various twitter exodus waves, it's a very similar pattern - huge increase followed by tail off, then another wave of increase followed by another tail off etc. I suspect the same thing will happen with Lemmy/Reddit. We all know reddit are going to continue to do stupid things prior to their IPO so it's likely there'll be more waves of influx followed by tail offs.
This is actually good as it's organic growth/loss. I can't think of an example where a big push by a company to get more users has resulted in a 'better' community, just a larger one. Organic growth/loss is much more likely to result in a better community as oppose to just a 'popular' one. Or, to put it another way, lets aim for quality not quantity.
Now that my instance has defeded from Hexbear I don't see much outright tankie stuff anymore and on the very rare occasions I do come across it, I just block the user. That said, I have noticed a growing trend of people calling anything slightly to the political left of Joe Biden either socialist, communist or tankie as though those terms were interchangeable, which they're not. Either way, if it bothers you, either ignore it, block the user, block the community or move your account to an instance that is defeded from the instances you are upset by.
Let's also not forget Lemmy is not mature software and has only become as heavily used as it is now about 3 months ago. There's a lot of features missing, particularly for admin and mod users, so we can either be patient and do what we can right now, fork Lemmy, create unofficial patches or not use it.
I do feel like we've become so used to highly polished, corporate solutions that do everything that we've lost our ability to be patient. For me, its vastly preferable to be somewhere where I'm not tracked, fingerprinted, advertised to and have my data sold but at the same time put up with a few idiosyncrasy's of the software than the alternative.