Hi @Shashi_Mulugu ,As per documentation there is only one way to retain old look 'n' feel is to disable unified shell.We tried to overlay the classes but that is not working . ThanksHimanshu

After enabling unified shell in AEM as a cloud service , the existing customized look and feel of author instance is impacted.Is there any way to override this unified shell css to make our existing header look and feel back again in the system. This is only for author instance. Any leads?  ThanksHi...

Scene7 queue is shared so make sure either you process in small batches as per your business priority or reach out to adobe support team to fine tune or allocate more resources for your program for scene7 sync. ThanksHimanshu

Supported format https://experienceleague.adobe.com/docs/experience-manager-cloud-service/content/assets/file-format-support.html?lang=en 

You can add extra options in the dialog multifield for each tab and add the icons accordingly .

Is this replicated to publish instance?

Check user permission to access /etc/folder assuming your publish page is open for all users ( no login required) .   Thanks Himanshu

Refere: https://experienceleague.adobe.com/docs/experience-manager-cloud-service/content/implementing/deploying/configuring-osgi.html?lang=en    

Check value of your ACS URL field as well .

Which version of acs commons you are using now?