AKS - Pods created by HPA trigger are getting terminated immediately after they are created

Question

When we had a look into the events in AKS, we observed the below errors for all the pods which were created and terminated:

2m47s       Warning   FailedMount         pod/app-fd6c6b8d9-ssr2t                         Unable to attach or mount volumes: unmounted volumes=[log-volume config-volume log4j2 secrets-app-inline kube-api-access-z49xc], unattached volumes=[log-volume config-volume log4j2 secrets-app-inline kube-api-access-z49xc]: timed out waiting for the condition

We already have 2 replicas running for the application so don't think that the error will be due to AccessModes of volumes.

Below is the HPA config:

apiVersion: autoscaling/v2beta1
kind: HorizontalPodAutoscaler
metadata:
  name: app-cpu-hpa
  namespace: namespace-dev
spec:
  maxReplicas: 5
  minReplicas: 2
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: app
  metrics:
    - type: Resource
      resource:
        name: cpu
        targetAverageValue: 500m

Below is the deployment config:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: app
  labels:
    app: app
    group: app
    obs: appd
spec:
  replicas: 2
  selector:
    matchLabels:
      app: app
  template:
    metadata:
      annotations:
        container.apparmor.security.beta.kubernetes.io/app: runtime/default
      labels:
        app: app
        group: app
        obs: appd
    spec:  
      containers:
        - name: app
          image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
          securityContext:
            allowPrivilegeEscalation: false
            readOnlyRootFilesystem: true  
            runAsNonRoot: true
            runAsUser: 1000
            runAsGroup: 2000
          imagePullPolicy: {{ .Values.image.pullPolicy }}
          resources:
           limits:
             cpu: {{ .Values.app.limits.cpu }}
             memory: {{ .Values.app.limits.memory }}
           requests:
             cpu: {{ .Values.app.requests.cpu }}
             memory: {{ .Values.app.requests.memory }}
          env:
          - name: LOG_DIR_PATH
            value: /opt/apps/
          volumeMounts:
          - name: log-volume
            mountPath: /opt/apps/app/logs
          - name: config-volume
            mountPath: /script/start.sh
            subPath: start.sh              
          - name: log4j2
            mountPath: /opt/appdynamics-java/ver21.9.0.33073/conf/logging/log4j2.xml
            subPath: log4j2.xml
          - name: secrets-app-inline
            mountPath: "/mnt/secrets-app"
            readOnly: true
          readinessProbe:
            failureThreshold: 3
            httpGet:
              path: /actuator/info
              port: {{ .Values.metrics.port }}
              scheme: "HTTP"
              httpHeaders:
              - name: Authorization
                value: "Basic XXX50aXXXXXX=="
              - name: cache-control
                value: "no-cache"   
            periodSeconds: 10
            successThreshold: 1
            timeoutSeconds: 1
            initialDelaySeconds: 60  
          livenessProbe: 
            httpGet: 
              path: /actuator/info
              port: {{ .Values.metrics.port }}
              scheme: "HTTP"
              httpHeaders:
              - name: Authorization
                value: "Basic XXX50aXXXXXX=="
              - name: cache-control
                value: "no-cache"    
            initialDelaySeconds: 300 
            periodSeconds: 5
            timeoutSeconds: 1 
            successThreshold: 1 
            failureThreshold: 3                                   
      
      volumes:
      - name: log-volume
        persistentVolumeClaim:
          claimName: {{ .Values.apppvc.name }}
      - name: config-volume
        configMap:
          name: {{ .Values.configmap.name }}-configmap          
          defaultMode: 0755    
      - name: secrets-app-inline
        csi:
          driver: secrets-store.csi.k8s.io
          readOnly: true
          volumeAttributes:
            secretProviderClass: "app-kv-secret"
          nodePublishSecretRef:
            name: secrets-app-creds
      - name: log4j2
        configMap:
          name: log4j2          
          defaultMode: 0755    
      
      restartPolicy: Always
      imagePullSecrets:
      - name: {{ .Values.imagePullSecrets }}

Can someone please let me know where the config might be going wrong?