Cannot filter issues in project by author present in included subgroup

Summary

This appear either a regression on #353899 (closed), or at least strictly related to it.

When filtering issues and using author or assignee filter, only direct project members are shown in autocompletion (even after you type first letters of their name). Previously, there were also users that have access to the project via group share.

The only difference to that ticket is that I added a subgroup and included that in the main group, instead of a totally unrelated group.

Steps to reproduce

1. Create a group
2. Create a subgroup
3. Add a different user to the subgroup with at least Reporter role
4. Include the subgroup in the parent group via "Invite group", with at least max role Reporter
5. Create a project within the parent group
6. Use the person you included in the subgroup to open an issue on the project
7. With a different user, try to go to the project list of issues, and filter by author.

Example Project

You can test the bug with a sample project I created.

What is the current bug behavior?

The other user who opened the issue will not be shown in the dropdown for filtering.

What is the expected correct behavior?

The dropdown will show the other user.

Relevant logs and/or screenshots

Output of checks

This bug happens on GitLab.com