When a new revision is created the deployment replicas is set to 1 by default in order to scale and check if the revision can be healthy.
A customer has a scenario as follows:

• Creates a revision that comes up without a problem and then scales down to zero as there is no traffic.
• Makes the revision image private or removes it from their internal registry.
• Issues a curl command that gets stuck (for some time) as there will be no pod coming up due to the image pull error that occurs.
• The revision scales down to zero but no error is shown or at least the user does not have a specific point where to look.

Upstream issue here: https://github.com/knative/serving/issues/14157

It seems that we also don't get the right output even if we keep faulty pod around using min-scale=1, also progressdeadline does not work.