Operator index image is missing old OpenShift Pipeline versions

Description of problem:

After a chat with DanielMesser in slack 

I checked old index images, and if a new version in a channel is populated, the old versions disappear. According to DanielMesser this behavior is not good. For example,  if you're running an image mirroring with oc mirror and select a specific version of an operator and the operator with that version is not in the index any more it breaks your image sync.

Here the index image tags where an version disappears:

# Checking v4.12-1678112379;->;2023-03-06;15:19:39
"openshift-pipelines-operator-rh.v1.8.2"
"openshift-pipelines-operator-rh.v1.9.1"
# Checking v4.12-1678123823;->;2023-03-06;18:30:23
"openshift-pipelines-operator-rh.v1.8.2"
"openshift-pipelines-operator-rh.v1.9.2"

Here my check script: github.com/rbo/check-operator-index-versions

Prerequisites (if any, like setup, operators/versions):

Steps to Reproduce

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Actual results:

Expected results:

Reproducibility (Always/Intermittent/Only Once):

Build Details:

Additional info (Such as Logs, Screenshots, etc):