Hi @hareeshr1179, thanks for your message, and welcome to Atlassian Community!
We plan to provide such a flag so that our Marketplace partners could test their changes without the deprecated fields. Once this becomes available, we’ll post a comment in Deprecation of the Epic Link, Parent Link and other related fields in REST APIs and webhooks. Please subscribe to new comments in this post to stay up-to-date and get notified once this becomes available.
We understand that this may not allow enough time for you to test your changes. We will monitor the usage of the old fields, and we will switch them off at any point after 30 Nov, when our monitoring indicates that it is safe to do so. We will also make sure to allow enough time for our Marketplace partners to test their apps with these fields switched off. We will not switch these fields off across production instances until we make sure that our Marketplace partners have had an opportunity to test their apps with these fields switched off.
Thanks,
Konstantin