It might also be related to equity. I was laid off and went from a mature startup to an earlier stage startup, and on paper my TC dropped by 50%. But neither company is public yet, so who tf knows what either company will be worth at the point either of them IPO. My base pay went up by about 5%.
So I guess depending exactly on the specifics, "my TC dropped by 50%" might not really be a very meaningful statement without more context.
In this case, the drop is literally 50% in W2 income, as I went from a public company with RSUs to a startup. In the previous job salary was higher and RSUs were a decent amount, even after stocks tanking. Startup equity is decent, but that's more of a lottery ticket than anything else.
So I guess depending exactly on the specifics, "my TC dropped by 50%" might not really be a very meaningful statement without more context.