+ X more assignee's icon is not visible on issue board by default
Problem
Currently the grey icon only becomes visible on hover.
see https://gitlab.com/gitlab-org/gitlab-ce/issues/33409 for example
Solution
quoting from: https://gitlab.com/gitlab-org/gitlab-ee/issues/1904
If there are 4 assignees, we can show them all, and if there are more than 4, we can use the fourth circle to indicate the number of remaining assignees
So the fourth grey circle with the number should be visible if more than 4 assignees..
@ClemMakesApps assigned this to you, as you worked on the original issue