I work for a tech company and like you said, I've almost been there for 4 years and apart from my own department I would genuinely struggle to name anyone else

I work for a tech company and like you said, I've almost been there for 4 years and apart from my own department I would genuinely struggle to name anyone else on my floor (~100 people). I could probably count the number of people I know on one hand. Whereas three years ago, I knew everyone's name across three floors. Tech turnover is just so high, even our C Suite have almost all changed twice since I've been here. I'm easily one of the longest standing members of staff and we have over 1,000 tech employees.