Here's the official changelog, quite a bit of which is more for use in a modern Desktop browser like Chrome or Edge:
- Birdwatch: We’ve added Birdwatch, a pilot program in the US of a community-driven approach to addressing misleading information on Twitter. Learn more here.
- Carousels: We’ve rolled out Image/Video Carousel ad formats for Promoted Tweets on Twitter.com.
- DMs: We’ve added social context information to message requests in your inbox. This should give you a better idea of who has sent the DM, and whether they’re someone you might know.
- Hover Labels: We’ve been working to improve and expand our hover labels! To start, we’ve added hover labels to the side navigation when it’s collapsed to help give you more context. We’ve also added them to the composer, media viewer sidebar, and the home timeline switch.
- Pre-Roll Ad Redesign: We’ve made a number of updates to Pre-roll video ads on Twitter.com to improve ad attribution and the overall user experience.
- Retweets: The Retweets button will once again display the Retweet and Quote Tweet menu instead of directly opening the Quote Tweet composer.
- Topics: Topic pills in the Suggested Topics module now have an “X” button which allows you to indicate when you’re not interested in a Topic.
- Verified Accounts: We’ve added an educational sheet for the verified badge, and a new flow for verified accounts to remediate issues and violations.
- DMs: The tombstone for sensitive media in DMs will now show more informative text in the button to display media, letting you know whether it’s a photo, video, or GIF.
- Emoji Picker: The recently used section in the emoji picker will now update when closing the picker, instead of in realtime. This will make it easier to select emojis from the recently used section without them reordering while you’re making selections.
- Misinformation Prompt: When you’ve selected Like or Retweet on an embedded Tweet that has been flagged as misinformation, you’re brought to the Web client and shown a confirmation prompt. This prompt now has a link for more information about the Tweet.
- Topics: Increased the size of the Topic pills in the Suggested Topics carousel on mobile devices.
- Topics: For recommended Topic Tweets, we’ve increased the size of the context header on the Tweet detail screen.
Plus a truck-load of bug fixes.
Quite a list, it's impressive how much goes into the Twitter PWA, helped by the fact that's now used on the web in general, so the changes are seen by vast user numbers.
As usual, some screenshots to illustrate some highlights:
Good stuff. You can grab or update the Twitter PWA-ified UWP client here in the Store.
PS. As a reminder, this application now trumps third party options like Tweetium UWP because of recent Twitter changes which knocked push notifications on the head. Along these lines, see also my (older) general round-up of ways to access Twitter under Windows 10 Mobile.