In order to avoid the incorrect parsing of the target argument you can call Net::OpenSSH (unmodified) constructor as follows:

$ssh = Net::OpenSSH->new('cyberark.internal.com',
                         user => 'me@admin@remote.host',
                         ...)
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Regarding the capture issue, well, you would have to show us the complete script and debugging output, otherwise it is impossible to know what is going on.

Also, I don't know how CyberArk does its magic. Maybe it sets a wrapper for the real OpenSSH ssh command, and that may interfere with some of the more advanced usages of the command as the ones required by Net::OpenSSH.