Having some problems with push mirroring

Dear all,

Hello, I'm Yohan Kim, one of the maintainers of the ftp.kr.debian.org (
ftp.kaist.ac.kr), which is a mirror mirroring from rsync://
syncproxy2.wna.debian.org/debian/.
Recently we have noticed that our sync is not occurring automatically since
2020-05-11 (approximately).
To resolve this issue, we have tested our script and now, to mitigate this
issue, we're syncing it manually.

As I think the push mirroring is not coming, could you please let me know
if there was change of key or our server is rejected for some reason?

Thank you for reading.

Sincerely,
Yohan Kim