While testing a migration activity, I executed the below steps:
We noticed that all the AD users and AD groups were successfully restored on the test server. However when we are checking the permissions of these users on the test server, they have been changed. The users and groups had “Publisher” rights on the actual server, however on the test server their role is changed to “viewer”. We checked the “maximum site role settings” of these individual users and they were shown as “Publishers or Interactors”, however on the workbook permission page, they were rest to “viewers”. I also checked the Groups to they belong to and the group also has “publisher” access.
I wanted to know whether this is happening due to mismatch of the authentication mode on both the servers.
You are correct! This is happening due to the mismatch of authentication types between the two Tableau Server installations. You'll want to install both as AD, or use the Site Export/Import functionality to map your AD users to local users on your destination Tableau Server: