There's huge precedent in many RPGs, going all the way back to the 80s, of having some (or most) encounters that you are just expected to die at, the first time. It's a pretty classic tradition of game design. Especially "off the critical path" encounters that are technically skippable. Almost every RPG I can think of that wasn't a total cakewalk had some encounters like this. You run into it unprepared, you get smashed, then you either come back later or you plan some new tactics in order to beat it.
In my opinion, this is good. Because the alternative to this is a game in which you just win every encounter on the first try, even without being prepared or knowing what you're doing. And in that scenario, nothing in the world feels dangerous.
