That almost has to be a change in ncurses or the Perl bindings to ncurses. Most terminal emulators have settable modes to determine whether to handle mouse events internally or pass escape codes to the program running on the terminal. Your change is from the terminal emulator processing mouse wheel events itself to passing them to the user program. Check your terminfo database and be prepared to dig into the alacritty sources — in my experience, the mouse-related escape codes tend to be under-documented.