Thanks for the report, there are multiple possible issues here.
First, I think Twitter blocked getting tweet info via OpenGraph outright for all non-browser consumers (like bots and crawlers etc.). Multiple people in our team can’t get tweet oneboxes in Whatsapp, Telegram and other apps since a couple of days ago.
Second, last week they announced Deprecation of legacy access tiers in the Twitter API - Announcements - Twitter Developers, for us that means that we can no longer get tweets from the /1.1/statuses/show route.
We added a fix for this yesterday by @jancernik FIX: Use Twitter API v2 for oneboxes and restore OpenGraph fallback (… · discourse/discourse@24c9053 · GitHub – that switches our code to use Twitter’s v2 API, which is the only remaining avenue for getting oneboxes. In our testing it works, but only if the API key is from a paid tier. I just checked, and it looks like here on meta we’re using a free tier API key (we’re working on a fix) and likely why it doesn’t work on your instance.
Note that Jan’s PR added OpenGraph fallback, but as he was working on it, Twitter blocked access to that too. There’s a very good chance that will never work (and we’ll remove the fallback code).
The bottom line is: without paying Twitter for API access, oneboxes might never work. It’s a sad state of affairs.