Is this also valid the other way around?
It’s not possible or at least not for now. That’s something that has to be implemented and the devs of Lemmy doesn’t seem to be interrested in that feature. Kbin is kind of something inbetween Lemmy and Mastodon, you be able to post on Lemmy and Mastodon, but i’m not sure about the future of kbin.
While Mastodon, Lemmy, Misskey and a lot other software plattforms are connected in the Fediverse. You should be aware, that different software work different on the Fediverse. Mastodon is designed liker Twitter/X, to be a Plattform posint short messages or news. Lemmy is more designed like a forum, not as user based as Mastodon, more in communities. There is a connection between a lot different Software Platforms on the Fediverse, but not every feature is on every plattform. So you are not able to downvote a Lemmy post from Mastodon. You have the option to interact with Lemmy posts with a Mastodon account and it’s a valid way to do it, but for the full experience on all Plattform, you should make yourself an account on every Plattform that is important for you.
I have never used the Mastodon app, i think a lot 3rd Party apps are better on Mastodon, so i don’t know how it looks, but Mastodon has, or had, a weird form in showing commet trees in my opinion.
seems like my instance, lemmy.zip, is on Hetzner as well
I already have seen some of those and sure it works…sometimes.
The new CEO of Mozilla, Laura Chambers, already said on march she want to reduce investment for mastodon and other products (VR, VPN, Relay). So this is just another part in reducing cost on section that doesn’t produce money. I’m not surprised. Sadly i have only a german source for that and the soure of them, bloomberg has a paywall.