Hallo Chamika
I don't know whether you were too hasty taking two steps in quick succession. Anyway to recap:
Step A: You upgraded your Moodle 3.2 to 3.8 and all were well after minor hick-up discussed here
https://moodle.org/mod/forum/discuss.php?d=394019#p1588617. For my understanding: You upgraded on the old 3.2 (by exchanging the Moodle code directory from 3.2 to 3.8)? Not on a copy, right? And the users could authenticate with the ActiveDirectory, before and after upgrade?
Step B: You migrated the site to a new server, obviously to a different IP address but also having a different domain name.
You said: "now moodle asking email confirmation again for all of yours who they actually done email authentication earlier" What is "earlier", in the 3.2? in the 3.8 in Step A? Why did they do that at all? A user set for authentication method ActiveDirectory never have to do any confirmation via e-mail!
N.B. The formal address may be correct in our subcontinent, but in the global village everybody is a netizen ;)