One of the things I don't like about Toronto's current e-things is that most of them can and frequently do slow abruptly with no warning for people behind them. If the rider uses the brakes, maybe you'll see a rear red light up, but if they just ease off the throttle there's no signs until you're running into them, and they're heavy enough to slow rapidly when the throttle is backed off (or so I assume from the visible results).

Riding behind one can be entirely too alarming as a result.