Maybe this is an Xorg issue ? I've tryed creating the Xorg cofig file for the second monitor as people on forums pointed that sometimes xorg point torward the wrong nvidia stuff and it outputs this :
X.Org X Server 1.21.1.15
X Protocol Version 11, Revision 0
Current Operating System: Linux debian 6.12.10-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.12.10-1 (2025-01-18) x86_64
Kernel command line: BOOT_IMAGE=/boot/vmlinuz-6.12.10-amd64 root=UUID=2a5eb3de-eb53-44bd-936f-dc7aaef7701f ro quiet
xorg-server 2:21.1.15-2 (https://www.debian.org/support)
Current version of pixman: 0.44.0
Before reporting problems, check http://wiki.x.org
to make sure that you have the latest version.
Markers: (--) probed, (**) from config file, (==) default setting,
(++) from command line, (!!) notice, (II) informational,
(WW) warning, (EE) error, (NI) not implemented, (??) unknown.
(==) Log file: "/var/log/Xorg.2.log", Time: Thu Jan 30 17:51:37 2025
List of video drivers:
amdgpu
ati
intel
nouveau
nvidia
radeon
vmware
modesetting
fbdev
vesa
(++) Using config file: "/root/xorg.conf.new"
(==) Using system config directory "/usr/share/X11/xorg.conf.d"
Number of created screens does not match number of detected devices.
Configuration failed.
(EE) Server terminated with error (2). Closing log file.