Lack of documentation and not knowing what the dependencies are for the system, not knowing what other service or function might break due to your changes.
But most importantly, the lack of automated testing. It becomes increasingly harder to ship your refactored code when you don't have the confidence that it will not break something else.
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Functions that are hundreds of lines long.
No coding style or standards followed.
Lack of documentation and not knowing what the dependencies are for the system, not knowing what other service or function might break due to your changes.
But most importantly, the lack of automated testing. It becomes increasingly harder to ship your refactored code when you don't have the confidence that it will not break something else.