Lower resolutions of monitor get blurried screen using nvidia driver in Debian 11

Question

The monitor of my laptop had several options for screen resolution before install nvidia driver on a Debian 11 system.

After installing the nvidia driver I get also several options but, besides the greatest one (2560x1600), the others all have "scaled" after the resolution scale.

The nvidia-settings display those possible resolutions in the image bellow -- notice the "Auto" grayed on the right side of the Resolution option, so I can't change frequency for a specific resolution.

I read a lot of posts in stackoverflow about changing the resolution using xrandr but without success.

Running xrandr I get:

Screen 0: minimum 8 x 8, current 1920 x 1200, maximum 32767 x 32767
DP-0 disconnected (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
DP-3 disconnected (normal left inverted right x axis y axis)
HDMI-0 disconnected (normal left inverted right x axis y axis)
DP-4 connected primary 1920x1200+0+0 (normal left inverted right x axis y axis) 344mm x 215mm
   2560x1600     60.00*+

I added a new resolution using xrandr, using --newmode option:

xrandr --newmode "1920x1200_60.00"  191.96  1904 2032 2240 2576  1200 1201 1204 1242  -HSync +Vsync

After this and running xrandr again:

Screen 0: minimum 8 x 8, current 1920 x 1200, maximum 32767 x 32767
DP-0 disconnected (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
DP-3 disconnected (normal left inverted right x axis y axis)
HDMI-0 disconnected (normal left inverted right x axis y axis)
DP-4 connected primary 1920x1200+0+0 (normal left inverted right x axis y axis) 344mm x 215mm
   2560x1600     60.00*+
  1920x1200_60.00 (0x223) 191.960MHz -HSync +VSync
        h: width  1904 start 2032 end 2240 total 2576 skew    0 clock  74.52KHz
        v: height 1200 start 1201 end 1204 total 1242           clock  60.00Hz

Now, when I try to add the enable the new resolution doing

xrandr --addmode DP-4 "1920x1200_60.00"

I get the error

 Error of failed request:  BadMatch (invalid parameter attributes)
  Major opcode of failed request:  140 (RANDR)
  Minor opcode of failed request:  18 (RRAddOutputMode)
  Serial number of failed request:  39
  Current serial number in output stream:  40

I tried to add the proper lines to /etc/X11/xorg.conf, and after rebooting but without success to:

...
Section "Monitor"

    # HorizSync source: edid, VertRefresh source: edid
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "CSO"
    HorizSync       99.0 - 99.0
    VertRefresh     40.0 - 60.0
    Modeline       "1920x1200_75.00"  245.25  1920 2064 2264 2608  1200 1203 1209 1255 -hsync +vsync
    option     "PreferredMode"  "1920x1200_75.00"
    Option         "DPMS"
EndSection
...

So, in summary I want to have a lower resolution in my laptop monitor but with the screen doesn't getting that little blurried what makes a pain for the eyes.

Anyone knows about other way to get this done or am I missing something?