404 error out of blue disabled my project completely

Yesterday my project was working and initializing correctly. Today, when I tried to continue my work, a 404 error appeared at startup and now it won’t initialize at all. None of the AI-generated fixes worked — it just refuses to start, and the terminal shows this:
Found a change in next.config.js. Restarting the server to apply the changes…
▲ Next.js 14.2.32

✓ Starting…
✓ Ready in 8.9s
○ Compiling /_not-found …
✓ Compiled /_not-found in 6.6s (479 modules)
GET /studio 404 in 6939ms
:warning: Blocked cross-origin request from 9100-firebase-studio-1757205338607.cluster-oayqgyglpfgseqclbygurw4xd4.cloudworkstations.dev to /_next/* resource. To allow this, configure “allowedDevOrigins” in next.config
Read more: next.config.js: allowedDevOrigins | Next.js

Absolutly no solution from those I’ve tried works.