Ever Had a 90-minute Interview?

I completed an "introductory 45-minute virtual interview session" and the conversation could've kept going longer had I not ended it. I've now been asked back for a "second round interview conducted either in person or virtually, whichever you prefer." This was with a government agency. The first interview was not structured but they got a good idea of who I am professionally. This second interview is 90-minutes long. What could the 90-minute interview possibly be about? The only thing I can think of is meet our other staff? (25 employees total).