I've been using hetzner for a couple years and have always used them for my high bandwidth services but I have only gotten that notice once despite being a very heavy user, and around the same time everyone else did around a year ago. Maybe they're gonna start to care? With all the price hikes and all. I ended up just getting more servers to level it all out.
However Hetzner does not have the best peerings, so bandwidth to some locations might be worse than you'd like.
I just wanted to put the given numbers into the scale of the cheapest baremetal servers available on the market, to illustrate that this is not an amount of data you'd have to consider for scaling. Realistically speaking, you'd want to have more then 2 nodes so you don't have to worry about rebooting/updates etc