I fixed my problem.
Renamed the file /etc/X11/mhwd.d/nvidia.conf to /etc/X11/mhwd.d/nvidia.conf.old.
Uncomment all lines at /etc/modprobe.d/mhwd-gpu.conf like this:
##
## Generated by mhwd - Manjaro Hardware Detection
##
#blacklist nouveau
#blacklist ttm
#blacklist drm_kms_helper
#blacklist drm
Followed by the commands:
sudo pacman -Rdd nvidia-utils lib32-nvidia-utils
sudo pacman -Rdd linux612-nvidia
sudo pacman -Rdd linux618-nvidia
(I got a backup lts kernel)
Now I’ve got:
inxi -G
Graphics:
Device-1: NVIDIA GM206 [GeForce GTX 960] driver: nouveau v: kernel
Display: x11 server: X.Org v: 21.1.21 with: Xwayland v: 24.1.9 driver: X:
loaded: modesetting dri: nouveau gpu: nouveau resolution: 1: N/A
2: 1920x1200~60Hz 3: 1920x1200~60Hz
API: EGL v: 1.5 drivers: nouveau,swrast
platforms: gbm,x11,surfaceless,device
API: OpenGL v: 4.5 compat-v: 4.3 vendor: mesa v: 25.3.3-arch1.1
renderer: NV126
API: Vulkan Message: No Vulkan data available.
Info: Tools: api: eglinfo, glxinfo, vulkaninfo de: xfce4-display-settings
x11: xdpyinfo, xprop, xrandr