At the time of writing, the Linux Mint project is still to announce the release of Linux Mint Debian Edition (LMDE) 4 but if you check out mirror services, you can grab the new version right now. The new update brings improvements that were shipped with Linux Mint 19.3 such as Cinnamon 4.4, new default software, a boot repair tool, and more.
According to the ISO status page, the 32- and 64-bit LMDE 4 images were approved for stable release in that last several hours. While no announcement has been made, you can download them by heading to the Linux Mint mirrors page, selecting a mirror, heading into the debian folder and looking for LMDE 4. If you cannot see the ISO in the mirror you chose, just look on another mirror and you should find a download link.
The stable release comes less than a month since the beta images were made available. If you tried the beta and found any issues be sure to check out the stable version as your issue may now be resolved.
If you’d prefer to wait for an official announcement of this version’s release you will only have to wait a couple of days. With LMDE 4 out of the way, attention will fully turn to Linux Mint 20 which is due for release sometime in the summer. Linux Mint 20 will mark the biggest update to the operating system since 2018.