The code and its dependencies
Readability, tests, outdated or vulnerable libraries: the audit takes stock without judgement, with priorities.
Hosting and operations
Access, backups, deployment, monitoring: this is often where the most urgent issues are. An app without a tested backup is an immediate risk.
A plan, not a verdict
The audit leads to a plan: stabilise, fix, then evolve. See taking over an existing project, keeping the product alive and the article on backups.