hyprland-git update to r101 do not fix it, only first boot work.
The values from
hyprctl monitors
Monitor eDP-1 (ID 0):
2880x1800@90.000000 at 0x0
description: California Institute of Technology 0x1402 (eDP-1)
make: California Institute of Technology
model: 0x1402
serial:
active workspace: 2 (2)
special workspace: 0 ()
reserved: 0 40 0 0
scale: 1.50
transform: 0
focused: yes
dpmsStatus: 1
vrr: 0
must be this
monitor=eDP-1, 2880x1800@90, 0x0, 1.5
But on first boot after fresh install scale is 1 not 1.5.
I changed it to 1.5, I can not read anything on scale 1 
Looks like it is easier if the user DIY and not a script extract the values with grep, awk .. for one and up to X monitors
If they can't do it at Hyprland, then I certainly can't.
xrandr
xrandr
Screen 0: minimum 16 x 16, current 1920 x 1200, maximum 32767 x 32767
eDP-1 connected 1920x1200+0+0 (normal left inverted right x axis y axis) 300mm x 190mm
1920x1200 89.91*+
1600x1200 89.91
1440x1080 89.93
1400x1050 89.92
1280x1024 89.91
1280x960 89.91
1152x864 89.80
1024x768 89.72
800x600 89.85
640x480 89.73
320x240 87.89
1680x1050 89.94
1440x900 89.83
1280x800 89.89
1152x720 89.83
960x600 89.70
928x580 89.74
800x500 89.80
768x480 89.62
720x480 89.45
640x400 89.60
320x200 87.62
1920x1080 89.93
1600x900 89.88
1368x768 89.74
1280x720 89.80
1024x576 89.65
864x486 89.72
720x400 89.87
640x350 89.05