The issue with your cross-post is that it links away from the viewer's local instance. Somehow, you've managed to link two posts in the same community together (/c/Privacy@lemmy.ml), where the only difference in this post is that you have the discuss.tchncs.de link. It would have been better if you managed to cross-post the other post from discuss.tchncs.de, such that users can get an instance agnostic link to the other post.
Although really that probably isn't your fault. They really need to make instance agnostic post and comment links a thing. Let the host instance decide the number, then the link can be https://yourinstance/post/<number>@theirinstance
. Rather than every instance assigning a different number to posts and comments independently.
Edit: wait a minute, your discuss.tchncs.de link is just the same lemmy.ml link, but in a different instance. That's not much good, you should just stick with the lemmy.ml post and let others view it from their own instance. For me, your post is https://lemm.ee/post/2087164, and there will be a different link for every instance that's federated with the community.
Like I say, they really need to make post links agnostic.