The server should group them. If two crossposts are in the same post listing, the server should combine them and add a property in the API to let us know it was combined.
Also, Lemmy has no concept of a "crosspost". All it does to check a "crosspost" is check if they have the same URL.
Your IP seems to have been blacklisted by Cloudflare and it thinks you're a malicious bot. You'd have to get in contact with Cloudflare to get your IP unblocked.
While I believe that this may be a hostile decision, it was inevitable. A lot of YouTube's revenue comes from ads. Use piped or something