At least on Arch Linux and Manjaro. There’s no official announcement yet.

Cinnamon is a desktop environment developed by the Linux Mint team. It has a classic layout by default and is highly customizable which makes it very popular among Linux users.

By the time of writing there’s no official announcement so I’m not aware of the complete changelog, but here’s a list of the known new features in Cinnamon 4.

What’s new in Cinnamon 4?

  • Better memory usage
  • Compositing performance enhancements
  • New task manager (forked from Icing Task Manager)
  • Changes on the Menu (there’s a bug with the search ordering, though)

I will update the list as far as I know more about it. It seems to me that it mainly contains under the hood performance boosts and not many UI changes.
Of course the new task manager is an exception. It supports window grouping and other modern features what Cinnamon was lacking so far. However for people that want to use the old layout, it is still available.

Linux Mint users haven’t received the update yet, it’s only available to Arch and Arch Linux based distros.