Vercel Crons is not working

Hello ! I don't know if it's a bug, but I don't even find the solution. I use Vercel for my Tanstack Start app. It works great, but if I add a cron job (with https://vercel.com/docs/cron-jobs/quickstart?framework=other), all of my routes api of the tanstack start (build step) are just broken (all 404). Like better auth is not working if I have just a api/hello.ts at the root of my project and deployed on Vercel. It works great on local (with build/start steps).