Corsair179's page

Yes, in general players get a secret perception check to detect a hazard before it does anything. Since the Vision of Dahak has a minimum proficiency required, they must be experts in perception and be actively Searching (DC 26).

CRB page 520 wrote:

During exploration, determine whether the party detects a hazard when the PCs first enter the general area in which it appears. If the hazard doesn’t list a minimum proficiency rank, roll a secret Perception check against the hazard’s Stealth DC for each PC. For hazards with a minimum proficiency rank, roll only if someone is actively searching (using the Search activity while exploring or the Seek action in an encounter), and only if they have the listed proficiency rank or higher.

Outstanding resource: https://www.youtube.com/watch?v=UQ7cXtW-dt4