So what is said....a different type electronic 'sweep' occurred. The comments lead me to think it's not the Secret Service....maybe it's a commercial company. They picked up a different type of frequency near the desk (oversized). So it's been removed and it'll be analyzed.
My humble guess?
First, it's likely a bug that was embedded. They will drill out the suspect area.
Who? Well....once you have the bug....the brand/model will come into play. Probably a customized bug....leading you to no company.
CIA? FBI? Mossad? FSB? Chinese? Brits? Former Biden crew? CNN? I might have a list of forty-odd folks.
Then I'd suspect whoever did this bug....probably has another dozen bugs around the entire White House....so there's going to be a massive 'drill' to take place. And it'll be repeated every single week.
But I'll add this one suspicion.....that this was a low-frequency bug, and it probably needed a bug-dump to someone who walks into the room. Figure here....it's someone 'trusted' on the Trump-staff, or the cleaning-crew.
Crazy crap? Yeah....planned out. Once they knew he wanted the over-sized desk....they went to work to design a special bug.