As I reported during the beta phase, LMDE (Linux Mint Debian Edition) 5 is based on the Debian GNU/Linux 11 “Bullseye” operating system series. More precisely, it is using the packages included in the Debian GNU/Linux 11.2 point release that arrived last year in December.
This means that Linux Mint Debian Edition 5 is powered by the long-term supported Linux 5.10 LTS kernel series, which will be supported until October 2023. On top of that, LMDE 5 “Elsie” comes with all the applications and packages included in the Linux Mint 20.3 “Una” release.