After the API Gateway is upgraded from any version to 9.4, the syslog headers and logs include the millisecond timestamp. The default time format in 9.4 is:
MMM d hh:mm:ss.SSS
The extra milliseconds format "SSS" causes issues in parsing with some monitoring tools.
This was introduced as an enhancement for customers that require the millisecond timestamp in their logs.
API Gateway: 9.4, 9.4 CR1
Configurable timestamp was introduced in 9.4 CR2 with a new audit-related cluster property - syslog.dateFormat. It allows format modification of the syslog date-time format.
Here are details about the property (end of the page):
To resolve this issue, upgrade to 9.4 CR2 first and then use this property per your needs.