@Ruokun Niu I'm glad that you were able to resolve your issue and thank you for posting your solution so that others experiencing the same thing can easily reference this!
Since the Microsoft Q&A community has a policy that "The question author cannot accept their own answer. They can only accept answers by others ", I'll repost your solution in case you'd like to "Accept " the answer. Accepted answers show up at the top, resulting in improved discoverability for others.
Issue: Customer shared - "AKS Cluster - Mutating admissions webhook does not trigger after a cluster restart. I was working with Dapr (https://dapr.io/) sidecars in a kubernetes cluster, where some of my pods have a sidecar injection. However, when I restart an AKS cluster, sometimes sidecar injection would fail, and I had to manually restart the pods to get it working again.
I talked to folks in Dapr and they suspected that it might be due to Mutating admissions webhooks and suggested me to ask here."
Solution: Cx shared - "My alternative solution is to use to the dapr injection watchdog (https://docs.dapr.io/concepts/dapr-services/operator/#injector-watchdog). It regularly checks the conditions of the sidecar and automatically triggers a restart if needed."
If your issue remains unresolved or have further questions, please let us know in the comments how we can assist.