I've been laid off a few times. I'd add one more "danger sign": you're not busy. If the firm/department doesn't seem to be achieving very much, it's a good sign that no-one's asking much of them. Which means the entire area is possibly for the chop.
But the line in the Excel sheet thing rings _incredibly_ true. It's actually surprisingly rare to be laid off by someone who knows you. Decision is nearly always made by people who've never met you and only have a cursory understanding of what your entire team does.
I've been laid off twice, and both times we were very busy. There were deadlines we were told were absolutely crucial to meet and we were burning ourselves out trying to meet them. The product we were making never saw the light of day and to this day we don't even know why.
But the line in the Excel sheet thing rings _incredibly_ true. It's actually surprisingly rare to be laid off by someone who knows you. Decision is nearly always made by people who've never met you and only have a cursory understanding of what your entire team does.