More significantly the new variables x and y in the block are Drop'd at the end of the block rather than at the end of the function. This can be significant if:

- Drop does something, like close a file or release a lock, or

- x and y don't have Send and/or Sync, and you have an await point in the function or are doing multi-threaded stuff

This is why you should almost always use std::sync::Mutex rather than tokio::sync::Mutex. std's Mutex isn't Sync/Send, so the compiler will complain if you hold it across an await. Usually you don't want mutex's held across an await.