One important thing about warrants and subpoenas is that they are often limited to strictly collecting data related to a specific investigation - not a fishing expedition.
> The judge placed some limits on the subpoena. He said police could use the images to identify suspects only in the arson and gun theft investigations. Detectives could not use the photos or video to pursue suspects in vandalism or other lesser crimes — even if police found such evidence.
> The subpoena would also be limited to professional camera equipment and would exclude reporters’ cell phone photos and videos.
This seems to fit the criteria - especially since police firearms were stolen.
The only red flag is that they are asking 5x different news organization to hand over journalist's raw recordings. I'd be highly skeptical of this subpoena if I was a judge - unless they could prove the journalists were likely the only ones at the time recording the incident, that they know were present, and it didn't apply to material involved in any specific reporting. Broad footage taken at a public event is always less concerning and less protected.
But at the same time tons of people are recording protests besides journalists and it might just be laziness on the police's part. Although that said, sometimes rioters intimidate people trying to film crimes being committed (as seen here: https://old.reddit.com/r/ActualPublicFreakouts/comments/hu9l...). And the police claim "the department was at a dead end in its investigations." So I'm not sure much outrage is warranted here, but I'd still probably lean on the safe side.