[Bug|Querier/Ingester]: Query parameter not working with /loki/api/v1/label/<name>/values endpoint.

[Lucostus]

Describe the bug
Querying the /loki/api/v1/label//values endpoint with a query parameter returns all values regardless of the provided matcher/query. This issue only occurs when querying between now and 6 hours. After 6 hours, the endpoint functions correctly and returns only the requested labels. This leads me to believe that the underlying bug may be related to the Ingester-query.

To Reproduce
Steps to reproduce the behavior:

1. Start a Loki "stack" (2.9.1) Here the main Docker-compose.yaml
2. Call the /loki/api/v1/label//values endpoint with a given label and try to query only a result.

Expected behavior
For example

http://localhost:3100/loki/api/v1/label/filename/values?query={filename=%22/var/log/wifi.log%22}

Returns:

{"status":"success","data":["/var/log/fsck_apfs.log","/var/log/fsck_hfs.log","/var/log/install.log","/var/log/shutdown_monitor.log","/var/log/wifi.log"]}

But it should only return "/var/log/wifi.log" and not all the files.

Environment:

• Infrastructure: OpenShift cluster 4.13
• Deployment tool: Openshift-logging -> Loki operator

Screenshots, Promtail config, or terminal output
no screenshots

[JoaoBraveCoding]

I believe this has been fixed in #10375, however, it wasn't added to any release, I've created two PR to backport the fix to 2.8.x and 2.9.x