Milestone burndown chart shows negative issues

Summary

My burndown charts show negative issues. For example:

Steps to reproduce

Open the milestone page e.g. https://gitlab.com/jebob/bad_milestone/-/milestones/1.

• Happens on both my Firefox and Chrome.
• Doesn't happen in a new repo.
• Bugged when others look at the milestone
• Bugged when I look at other milestones on the same project

Example Project

What is the current bug behavior?

I see negative issues open on the burndown chart.

What is the expected correct behavior?

I should see a typical burndown chart where the number of remaining issues is strictly non-negative.

Relevant logs and/or screenshots

Other examples

Output of checks

This bug happens on GitLab.com