Vivaldi 2.1 stable based on Chromium 70 has been released for Windows, Mac, and Linux on October 25, 2018, and is available for download. 2.1 version of Vivaldi improves Quick Commands feature, turns on AV1 codec support and Picture in Picture feature was pulled at RC stage at the last moment as it was not stable, Vivaldi team promises to offer it in a future update.
Vivaldi 2.1
This version puts emphasis on Quick Commands and it now lets you
- Create and search notes
- Zoom In/out and reset Vivaldi browser UI

You can also assign shortcuts to UI Zoom in/Out in Keyboard settings. To get started, press F2 to open Quick Commands menu and type UI, create notes,etc to start trying the new improvements added to QC.
Vivaldi with AV1 codec support
Vivaldi 2.1 has got AV1 codec support, but to watch AV1 videos on YouTube, you still need to visit YouTube test tube page and enable AV1 support, then head over to AV1 beta launch Playlist and play a clip and check stats for nerds for AV1 confirmation, for more details, read this.
The browser internal pages, Vivaldi://restart and Vivaldi://quit now work, so you may want to use them when needed.
Similar read: Fastest way to restart Firefox 62 after developer toolbar removal is this
Download Vivaldi 2.1 and check Vivaldi blog post for more details.