I have a shortcut on my shell:startup to open Pageant with my key and after start wsl-ssh-pageant using WSL socket:
"C:\Program Files\PuTTY\pageant.exe" "C:\Users\lucsavc\lucsavc.ppk" -c "C:\Users\lucsavc\software\wsl-ssh-pageant\wsl-ssh-pageant-amd64-gui.exe" --systray --wsl "%TMPDIR%\wsl-ssh-pageant.sock"
When shuting down the computer normally, seems that systray application is not stopped and the socket file is left there.
So next start, application won't start as socket is already there.