I don't think this has anything to do with the jira server. Apparently, the JIRA REST Java Client library require Java 21, but you are running XWiki with Java 17. So I suspect moving your XWiki instance to Java 21 should work too.
In any case, it does not make much sense for the Jira extension to depend on something that require Java 21 since it's supposed to support XWiki 14.10+ (which means requiring Java 17 max, and Java 11 ideally). I guess it means there is no automated test which use this library.
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