Milestones page on Gitlab.com throws a 500 error

Summary

When trying to access my milestones page on my Gitlab.com group https://gitlab.com/groups/sis-cc/-/milestones,
An error 500 is returned: "Whoops, something went wrong on our end."

Steps to reproduce

Try opening this page: https://gitlab.com/groups/sis-cc/-/milestones

What is the current bug behavior?

Accessing the list of milestones for a group of projects is no longer possible, even though individual milestones are still accessible (e.g. https://gitlab.com/groups/sis-cc/.stat-suite/-/milestones/27), and it is still possible to create new milestones using the GitLab API v.4.

What is the expected correct behavior?

When I click on https://gitlab.com/groups/sis-cc/-/milestones, it should display my list of milestones.

Relevant logs and/or screenshots

Output of checks

This bug happens on GitLab.com