It probably is bugged.
But Trump has brought in people like McMaster and Powell at the NSC who have access to all this kind of stuff and are undermining him right under his nose.
All phone calls with heads of state are transcribed. So, of course, it’s bugged. Trump knows it’s bugged. So does the recipient.
The scandal here is not that there is a transcript. The scandal is that something THIS sensitive got leaked in its complete form.
We are starting to enter unknown territory here as far as the undermining of a president goes.