Debug logs not available in syslog

[Shivakishore14]

Running Goofys with the debug flags on --debug_s3 --debug_fuse

goofys --debug_s3 --debug_fuse bucket /path

does not log any debug logs to syslog, only info logs are pushed to syslog

$ tail -f /var/log/messages
Sep  6 09:23:05 ip-10-125-253-247 /usr/sbin/goofys[10751]: main.INFO File system has been successfully mounted.

but if I run the Goofys on foreground with -f flag, this prints out debug log to stdout

goofys --debug_s3 --debug_fuse -f bucket /path

2022/09/06 09:33:20.396465 s3.DEBUG HEAD https://s3.amazonaws.com/my-bucket = 403 [us-east-1]
2022/09/06 09:33:20.399462 s3.DEBUG DEBUG: Request s3/HeadObject Details:
---[ REQUEST POST-SIGN ]-----------------------------
HEAD /my-bucket/7xynkjxxxxe HTTP/1.1
Host: s3.amazonaws.com
User-Agent: aws-sdk-go/1.38.7 (go1.19; linux; amd64)

Is this a bug? or is this the expected behavior?