I guess there is no way to download the standalone version with a version bought on steam?
Yes, there is.
Make an account on factorio.com if you don't have one yet
Go to your profile page (click on your name on the top right)
Scroll down to connect your Steam account with your Factorio account ...

As a side note, the game was working properly just a week ago and I can't figure out which packet I updated recently.

Look into your /var/log/pacman.log – it contains a history of package installations and updates.

I would also suspect your video drivers. I've seen this hang quite a few times ...

I have recently had an inexplicable decline in performance (stuttering and long freezes) in Factorio on Debian Linux with Intel GPU. It turned out the problem was not using the KMS driver: https://forums.factorio.com/viewtopic.php?f=49&t=21205

I'm not sure how this works in Arch, but it might be ...

Steam works properly.

I tried both : launching from steam and launching the binary directly (which in turns starts steam). Same problem for both.

Hey,

I'm playing factorio (through steam) on updated archlinux (laptop) since about a month without any issue.
I don't know what was updated (archlinux has daily updates (rolling release)) and keep every package to the most recent version.

That being said, factorio stopped working this week. The ...