At my last job, everybody loved to complain. The developers, the tech support, the salespeople, even management; I never really could understand it.
For the most part, all the complaints people had were split between the customers, third parties we needed to work with, and technology in general (slow internet, old computers, etc...). Though to their credit, I never once heard a complaint about other coworkers or departments except in jest, so it's not as though it felt like the work environment was a toxic workplace.
But this culture of complaining created something of a disconnect between me and many coworkers and I don't think I ever found the correct way to deal with it before I left that job. Several times I tried to get in on complaining and add my own complains to the pyre that was perpetually burning in the office, but they were never received with much enthusiasm. I expect that it was because they were insincere; I've never been big on complaining about things I couldn't change so I suppose I wasn't any good at trying to pretend like I was.
For my relatively short time there, this had been a baffling social experience. I'm sure I'll encounter other workplaces where this is the norm in the work culture since there are many people who like to complain all the time about anything. I've never had an issue with people when I'd meet them out in the world, but when it is sort of ingrained in the culture, it feels like a whole different beast that I have no idea how to handle correctly.