When I create a tag on Bitbucket Cloud the webhook notify Jenkins for a new tag. But the jenkins plugin does not handle it has a SCM event of kind tag but as branch created event.

The PushHookProcessor should be changed (line 165) to check of which kind of event is the notification.

if (change.isClosed()) {
	result.put(new BranchSCMHead(change.getOld().getName(), type), null);
} else {
	// created is true
	Reference newChange = change.getNew();
	SCMHead head = null;
	if ("tag".equals(newChange.getType())) {
		head = new BitbucketTagSCMHead(newChange.getName(), newChange.getDate().getTime(), type);
	} else {
		head = new BranchSCMHead(newChange.getName(), type);
	}
...
}

It is also needed add date to the com.cloudbees.jenkins.plugins.bitbucket.api.BitbucketPushEvent.Reference.

I also suggest to configure the ObjectMapper in payload parser (JsonParser) to use the ISO8601DateFormat that comes with jackson instead the custom.
Use a specific deserialiser for BitbucketCloudRepository.updatedOn where BB sends an invalid ISO8601 date format (6 decimal for milliseconds field instead 3 that cause date parse error)