I actually didn’t hate the last episode too much, putting all else aside and regarding it just all on its own. I like the idea that the titans come back from their super big world saving mission and everything isn’t all perfect honky dory they all lived happily ever after, and the idea of opening an arc where Terra returns but isn’t a hero wasn’t the most shit idea in the world to me, just as an idea and an introduction, since we never got to see how it might’ve turned out.
But I definitely agree that it was an awkward as shit last episode to leave off on and just feels weird and dumb without anything after it to follow it up. It wouldn’t have been a shit episode if there were more seasons after that, but it is shit now because there aren’t more seasons. And yes, the episide before it was a great series finale before that next and last episode fucked up.