https://pve.proxmox.com/wiki/FAQ#faq-support-table
Proxmox VE Version Debian Version First Release Debian EOL Proxmox EOL
Proxmox VE 7.x
Debian 11 (Bullseye)
2021-07
tba
tba
Proxmox VE 6.x
Debian 10 (Buster)
2019-07
2022-07
2022-07
Proxmox VE 5.x
Debian 9 (Stretch)
2017-07
2020-07
2020-07
Proxmox VE 4.x
Debian 8 (Jessie)
2015-10
2018-06
2018-06
Proxmox VE 3.x
Debian 7 (Wheezy)
2013-05
2016-04
2017-02
Proxmox VE 2.x
Debian 6 (Squeeze)
2012-04
2014-05
2014-05
Proxmox VE 1.x
Debian 5 (Lenny)
2008-10
2012-03
2013-01