PSA: Twitter has changed so visitors need to be logged in to read tweets - if you click a link to a tweet it will redirect you to a login page instead of showing you what has been posted.
This means the archive websites can no longer archive tweets.
As it stands right now at the time of posting, this hasn't broken our embed system, so as a temporary (and unfortunately archaic) workaround you can embed the tweet into a post, archive the thread page, then edit a link to it into your post. As a test I tried archiving the page where I embedded Valefor's reaction to the Pippa/Camelot drama,
and you can see the embedded tweet still shows up in the archive, though you need to scroll down because the archive site doesn't seem to read the exact post hash in the URL. Also remember this won't work for our read-only threads, like those in the Rec Room.
If anyone has a more elegant solution it would be appreciated - and I'd like to stress that having to do a bit of a runaround to archive something shouldn't be an excuse to get lazy with archiving. You never know when a tweet could be deleted, either due to someone engaged in drama realising a post was a bad idea, or a false report getting their account suspended. Screenshots can be helpful for thread readability but they do not prove legitimacy - it is very easy to create fake screenshots with Inspect Element, and if a vtuber involved in a scandal accuses you of faking a screenshot it is your word against theirs, and their fans will likely not believe you.