The documentation for audit configuration here mentions:

"The audit file rotates at the same time as the server log file."

However, it doesn't seem this is always the case. For example, on restart by default the system log will be "rotated" (or backed up) while the audit file will stay the same. I suggest something more specific like "Log rotation via a SIGUSR1 signal or a logRotate command affects the audit file as well as the server log file" or something along those lines. This is to avoid confusion as users/customers might expect audit file to be rotated too on startup when logAppend is false.

Thanks.