issue_40832

Setup:

1. Add DATABASE_URL TO .env or .env.local
2. Make database migration

Steps to reproduce:

1. Set mode to production in .env or .env.local
2. Open project in browser
3. Add value to title field
4. Submit => OK
5. Submit again (different value) => FAIL (This value is already used)
6. Clear cache (php bin/console cache:clear)
7. Submit again => OK
8. Submit again => FAIL
9. Set to dev mode
10. Submit => OK
11. Submit again => OK