Founders who switched dev agencies: what was the biggest nightmare during the handoff? (I will not promote)

Curious about this specifically from founders who outsourced some or all of their product development. If you’ve ever switched freelancers/agencies or had a developer unexpectedly disappear… what was actually difficult about taking the product over? I’m not talking about whether the code itself was good or bad. I’m more curious about the operational side… things like GitHub access, cloud accounts, databases, domains/DNS, app store accounts, API accounts, production credentials, deployment knowledge, backups, etc. Did your company already control everything, or did you discover during the handoff that important pieces were still sitting in accounts owned by the old developer/agency? And if the handoff went badly, what specifically caused the most pain and how long did it take to untangle? I’m trying to understand whether messy technical ownership during agency/freelancer transitions is actually common or just something that shows up in horror stories online.