Burndown Chart: Completion rate is not correct

Summary

Milestone 11.8 shows a completion rate of 62%, but it's only 47%.

Steps to reproduce

See milestone 11.8 in group gitlab-org on gitlab.com

Example Project

See milestone 11.8 in group gitlab-org on gitlab.com

What is the current bug behavior?

The milestone completion rate does not match the actual completion state. 316 closed issues out of 666 issues are 47%.
Moreover, the graph shows around 2/3 of remaining work, while the completion rate says 1/3 of remaining work ...

What is the expected correct behavior?

The completion rate should match the relation between closed and total issues.

Relevant logs and/or screenshots

image

Output of checks

This bug happens on GitLab.com

Possible fixes

  1. check the new algorithm to calculate and render a milestone's burndown chart.