Summary:

Jira server allows setting maximum character limit upto 2147483647 using the flag

jira.text.field.character.limit

as per https://confluence.atlassian.com/adminjiraserver072/configuring-advanced-settings-828788222.html 

While Jira cloud has no such config and defaults to 32767 characters as highlighted at https://jira.atlassian.com/browse/JRACLOUD-63007 . 

As https://jira.atlassian.com/browse/JRACLOUD-64351 is still open, migrations truncate big comments which are supported in server to cloud limit with a log message

/rest/migration/latest/check/c215ed7c394b4a41c585b9a512889fb32d097748 [c.a.j.m.e.core.comment.CommentExporter] Truncated text "xxxxx -..." to cloud limit of 32767 chars

ASK:

This suggestion is opened so JCMA doesn't truncate the comments and instead splits the comments into multiple entries. 

For descriptions maybe the description could be attached as a text file rather than deleting.