[release-5.4] $labels.instance is empty in the message when firing FluentdNodeDown alert

Description of problem:

When firing FluentdNodeDown alert, the alert message is missing "$labels.instance" as follows.
As a result, it does not honor "$labels.instance" label in the alert message. Check the image capture file together please.

Displayed messages:
~~~
Prometheus could not scrape fluentd for more than 10m.
~~~

Alert rule definition:
~~~

name: logging_fluentd.alerts
rules:
alert: FluentdNodeDown
annotations:
message: Prometheus could not scrape fluentd {{ $labels.instance }} for more <--- HERE
than 10m.
summary: Fluentd cannot be scraped
expr: absent(up

== 1)
for: 10m
labels:
namespace: openshift-logging
service: fluentd
severity: critical
~~~
Is it expected result ? How to display the "$labels.instance" label in the alert message ?

Version-Release number of selected component (if applicable):

$ oc version
Client Version: 4.9.23
Server Version: 4.9.23
Kubernetes Version: v1.22.3+b93fd35

$ oc get csv
NAME DISPLAY VERSION REPLACES PHASE
cluster-logging.5.4.0-138 Red Hat OpenShift Logging 5.4.0-138 cluster-logging.5.3.5-20 Succeeded
elasticsearch-operator.5.4.0-152 OpenShift Elasticsearch Operator 5.4.0-152 elasticsearch-operator.5.3.5-20 Succeeded

How reproducible:

You can always reproduce this when firing the "FluentdNodeDown".

Steps to Reproduce:
1.
2.
3.

Actual results:

Missing the "$labels.instance" value in the alert messages, even though the label is configured in the alert rules.

Expected results:

The "$labels.instance" value should be displayed as the alert rule is defined.

Additional info: