Workload insane, but headcount flat? What's going on?

My team's been absolutely swamped for the last quarter. We're working overtime just to keep up, and frankly, we're stretched thin. Yet, when I look at our headcount, it hasn't changed. No one's left, and certainly no one new has joined. It's like we're expected to do more with the same number of people, if not fewer because people are burning out. I've tried asking my manager if we're getting any additional support or if there are plans to backfill any gaps, but the answers are always vague – something about 'optimizing existing resources.' It's frustrating and honestly, unsustainable. Makes you wonder if they're quietly trying to get more out of us before making any bigger decisions.