[email protected] reposts /r/steamdeck reddit posts to itself automatically (as do all @lemmit.online communities). You're not really meant to engage with these posts directly, and it works better for images/news syndication than for actual community discussion.
As I understand it, lemmit.online is an instance set up to mirror content from reddit. It automatically copies the titles and content from communities on reddit so you can view them on Lemmy.
What’s being linked to here is the Lemmy clone of /r/steamdeck