Screenfetch vs fastfetch difference

Is there any reason for this different behaviour?

Hmm…fastfetch looks fine here.

Do you have eos-hooks installed?

Also, what is the contents of /etc/os-release

sudo pacman -Qq eos-hooks
eos-hooks

 alex@alex-hpnotebook  ~  cat /etc/os-release 
NAME="Arch Linux"
PRETTY_NAME="Arch Linux"
ID=arch
ID_LIKE=arch
BUILD_ID=rolling
ANSI_COLOR="38;2;23;147;209"
HOME_URL="https://archlinux.org/"
DOCUMENTATION_URL="https://wiki.archlinux.org/"
SUPPORT_URL="https://forum.archlinux.org/"
BUG_REPORT_URL="https://archlinux.org/help/"
PRIVACY_POLICY_URL="https://archlinux.org/privacy-policy/"
LOGO=archlinux-logo

Yeah, it looks like you no longer have eos-hooks installed.

reinstalling it did nothing

That is because it is a hook. It only runs when the relevant package is updated. Try running it manually with

sudo /usr/bin/eos-hooks-runner os-release
alex@alex-hpnotebook  ~  sudo /usr/bin/eos-hooks-runner os-release
 alex@alex-hpnotebook  ~  cat /etc/os-release                                                   
NAME="Arch Linux"
PRETTY_NAME="Arch Linux"
ID=arch
ID_LIKE=arch
BUILD_ID=rolling
ANSI_COLOR="38;2;23;147;209"
HOME_URL="https://archlinux.org/"
DOCUMENTATION_URL="https://wiki.archlinux.org/"
SUPPORT_URL="https://forum.archlinux.org/"
BUG_REPORT_URL="https://archlinux.org/help/"
PRIVACY_POLICY_URL="https://archlinux.org/privacy-policy/"
LOGO=archlinux-logo
 alex@alex-hpnotebook  ~  fastfetch 
                  -`                     alex@alex-hpnotebook
                 .o+`                    --------------------
                `ooo/                    OS: Arch Linux x86_64
               `+oooo:                   Host: HP Notebook
              `+oooooo:                  Kernel: Linux 6.18.18-1-lts
              -+oooooo+:                 Uptime: 3 hours, 50 mins
            `/:-:++oooo+:                Packages: 1563 (pacman), 12 (flatpak)
           `/++++/+++++++:               Shell: zsh 5.9
          `/++++++++++++++:              Display (BOE06A5): 1366x768 in 16", 60 Hz [Built-in]
         `/+++ooooooooooooo/`            DE: KDE Plasma 6.6.2
        ./ooosssso++osssssso+`           WM: KWin (Wayland)
       .oossssso-````/ossssss+`          WM Theme: Breeze
      -osssssso.      :ssssssso.         Theme: Breeze (Dark) [Qt], Breeze-Dark [GTK2], Breeze [GTK3]
     :osssssss/        osssso+++.        Icons: breeze-dark [Qt], breeze-dark [GTK2/3/4]
    /ossssssss/        +ssssooo/-        Font: Noto Sans (10pt) [Qt], Noto Sans (10pt) [GTK2/3/4]
  `/ossssso+/:-        -:/+osssso+-      Cursor: Bibata-Modern-Amber (24px)
 `+sso+:-`                 `.-/+oso:     Terminal: konsole 25.12.3
`++:.                           `-/+/    CPU: AMD A10-9600P RADEON R5, 10 COMPUTE CORES 4C+6G (4) @ 2.40 GHz
.`                                 `/    GPU 1: AMD Radeon R5 Graphics [Integrated]
                                         GPU 2: AMD Radeon R7 M340 [Discrete]
                                         Memory: 2.94 GiB / 6.73 GiB (44%)
                                         Swap: 357.63 MiB / 16.60 GiB (2%)
                                         Disk (/): 27.93 GiB / 223.07 GiB (13%) - btrfs
                                         Disk (/home): 25.38 GiB / 899.48 GiB (3%) - ext4

What does file /etc/os-release show?

file /etc/os-release
/etc/os-release: ASCII text

That is the problem.

Try this:

sudo rm /etc/os-release
sudo ln -s /usr/lib/os-release /etc/os-release

LOL

 alex@alex-hpnotebook  ~  cat /usr/lib/os-release 
NAME="EndeavourOS"
PRETTY_NAME="EndeavourOS"
ID="endeavouros"
ID_LIKE="arch"
BUILD_ID=rolling
ANSI_COLOR="32;1;24;144;200"
HOME_URL="https://endeavouros.com"
DOCUMENTATION_URL="https://discovery.endeavouros.com"
SUPPORT_URL="https://forum.endeavouros.com"
BUG_REPORT_URL="https://forum.endeavouros.com/c/general-system/endeavouros-installation"
PRIVACY_POLICY_URL="https://endeavouros.com/privacy-policy-2"
LOGO="endeavouros"

 alex@alex-hpnotebook  ~  fastfetch              
                     ./o.                   alex@alex-hpnotebook
                   ./sssso-                 --------------------
                 `:osssssss+-               OS: EndeavourOS x86_64
               `:+sssssssssso/.             Host: HP Notebook
             `-/ossssssssssssso/.           Kernel: Linux 6.18.18-1-lts
           `-/+sssssssssssssssso+:`         Uptime: 4 hours, 1 min
         `-:/+sssssssssssssssssso+/.        Packages: 1563 (pacman), 12 (flatpak)
       `.://osssssssssssssssssssso++-       Shell: zsh 5.9
      .://+ssssssssssssssssssssssso++:      Display (BOE06A5): 1366x768 in 16", 60 Hz [Built-in]
    .:///ossssssssssssssssssssssssso++:     DE: KDE Plasma 6.6.2
  `:////ssssssssssssssssssssssssssso+++.    WM: KWin (Wayland)
`-////+ssssssssssssssssssssssssssso++++-    WM Theme: Breeze
 `..-+oosssssssssssssssssssssssso+++++/`    Theme: Breeze (Dark) [Qt], Breeze-Dark [GTK2], Breeze [GTK3]
   ./++++++++++++++++++++++++++++++/:.      Icons: breeze-dark [Qt], breeze-dark [GTK2/3/4]
  `:::::::::::::::::::::::::------``        Font: Noto Sans (10pt) [Qt], Noto Sans (10pt) [GTK2/3/4]
                                            Cursor: Bibata-Modern-Amber (24px)
                                            Terminal: konsole 25.12.3
                                            CPU: AMD A10-9600P RADEON R5, 10 COMPUTE CORES 4C+6G (4) @ 2.40 GHz
                                            GPU 1: AMD Radeon R5 Graphics [Integrated]
                                            GPU 2: AMD Radeon R7 M340 [Discrete]
                                            Memory: 3.08 GiB / 6.73 GiB (46%)
                                            Swap: 390.73 MiB / 16.60 GiB (2%)
                                            Disk (/): 27.93 GiB / 223.07 GiB (13%) - btrfs
                                            Disk (/home): 25.38 GiB / 899.48 GiB (3%) - ext4

Thanks, you rock!!