Enable Advanced Search on Gitlab (ElasticSearch integration)
The search function is quite poor without it.
It's an ee only feature, but afaik Arch's gitlab is ee.
https://docs.gitlab.com/ee/integration/elasticsearch.html
As a note, historically, Gitlab is very slow with supporting new major versions of ElasticSearch.
As another note, the initialization is not visible anywhere and you can merely guess its progress from viewing sidekiq graphs.
Also, if Advanced Search is enabled but misconfigured, it breaks the search function completely, but the rest of Gitlab works fine.
If needed, I can help with this, but it should be quite straightforward.