In service desk, is no longer possible to add a link to a previous comment in the issue. When adding the link to the comment, for example https://support.atlassian.com/browse/CSP-122610?focusedCommentId=4487141&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-4487141 ,if the customer click on the link, he is redirected to https://support.atlassian.com/servicedesk/customer/comment-4487141 wityh the error message:

The Service Desk you are trying to view does not exist.

Tested in SAC.