Mirroring repository from GitHub to GitLab stopped working

Summary

Mirroring repository from GitHub to GitLab stopped working.

We haven't changed any settings (not on GitLab, not on GitHub) yet today synchronization stopped working and now no pipelines are run and it is already 6h since last synchronization even though many commits were added today.

Please advise as there is no documentation nor guide to fixing that kind of issues.

Is there any way of checking why synchronization is not being performed/why it fails?

Affected repository: https://gitlab.com/arkadiusz.wasilonek/packhelp

Steps to reproduce

1. Go to https://gitlab.com/arkadiusz.wasilonek/packhelp/commits/master
2. Check in UI when was last synchronization

What is the current bug behavior?

No synchronization from GitHub to GitLab for 6h now.

What is the expected correct behavior?

Synchronization is performed within minutes. If Error occurs - there is notification why synchronization was not performed or why it failed.

Relevant logs and/or screenshots