They do, you can see them on closer videos taken.
There is no federal "police" department. There's a number of federal agencies that do "law" enforcement and similar, but none of them are police. US Police departments are a part of incorporated cities. Outside of such cities, you get sheriffs. Between states you get the FBI, Treasury, Marshalls, etc.
These people were being taken to a federal courthouse, implying that they were federal agents, the only groups in Portland at the moment are ICE and the US Marshall service. The former has a fairly terrible human and constitutional rights record so I would guess it was probably them, but who knows - we know that they've had people "arrested" but have no record of the arrest. Which means it was an abduction by the federal gov with the intent to terrorise and escalate the conflict.
Which means that the OPB report is being intentionally misleading. Which is unsurprising for much of the media covering the events.
This doesn't come off as an honest criticism, as even having the specific agency insignia would just be blown off.