Comment 2 for bug 1942256

This is a workaround that works for me:

function my_fixStartup() {
    xfconf-query -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Super>Up' -r
    xfconf-query -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Super>Down' -r
    xfconf-query -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Super>Left' -r
    xfconf-query -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Super>Right' -r

    xfconf-query -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Shift><Super>Left' -r
    xfconf-query -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Shift><Super>Right' -r
    xfconf-query -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Primary><Super>Left' -r
    xfconf-query -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Primary><Super>Right' -r

    xfconf-query -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Super>Up' -n -t string -s 'tile_up_key'
    xfconf-query -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Super>Down' -n -t string -s 'tile_down_key'
    xfconf-query -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Super>Left' -n -t string -s 'tile_left_key'
    xfconf-query -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Super>Right' -n -t string -s 'tile_right_key'

    xfconf-query -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Shift><Super>Left' -n -t string -s 'tile_up_left_key'
    xfconf-query -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Shift><Super>Right' -n -t string -s 'tile_up_right_key'
    xfconf-query -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Primary><Super>Left' -n -t string -s 'tile_down_left_key'
    xfconf-query -c xfce4-keyboard-shortcuts -p '/xfwm4/custom/<Primary><Super>Right' -n -t string -s 'tile_down_right_key'
}

I was checking for differences from this (when setting through GUI):
xfconf-query -v -l -c xfce4-keyboard-shortcuts

Br