将fastcgi_pass从网络套接字切换到unix套接字后，Laravel“页面因不活动而过期”

Question

I'm running a website on nginx and was using a network socket so far to process php, with the following conf line

fastcgi_pass localhost:8000;

The problem is this socket points to php7.0 and I wanted to upgrade to php7.2 (which is installed on the server). I changed the line to the following

fastcgi_pass unix:/run/php/php7.2-fpm.sock;

The php is indeed executed, but whenever I try to log into my website, I get an error message from laravel "The page has expired due to inactivity". Nothing is logged so I don't have any idea what's going on...

Any idea why switching to a unix socket would break that?