Duo Developer not showing up in mention autocomplete

Summary

The @duo-developer-gitlab-org service account is not showing up in @-mention autocomplete dropdowns in AI gateway for most people although it is configured to be triggered by @-mention.

Manually completely typing out the account will make the mention work correctly.

This also does not affect everybody. The autocomplete dropdown works correctly for e.g. @thomas-schmidt and @mlapierre. It also seems to work locally.

Steps to reproduce

1. Go to an MR or issue in AI gateway repo, like gitlab-org/modelops/applied-ml/code-suggestions/ai-assist!4926 (merged)
2. Try to @-mention @duo-developer-gitlab-org
3. Observe that it does not show up in the auto-complete dropdown, although it is configured.
4. Observe that the service is correctly showing up in Assignee dropdowns when filtering for duo-..

What is the current bug behavior?

Service Account not showing up in Mention autocomplete

What is the expected correct behavior?

Service Account correctly being shown in autocomplete when typing out the name.