I don't think budget is the problem with this maze. It clearly is one of the best looking mazes HHN has done in terms of production value.
I think the issue lies with allocating that budget and what I'm guessing is "studio notes."
For example, I'm willing to bet the studio pushed the idea of doing a season 3 scene into the maze. They wanted their Scoops Ahoy and Starcourt Mall to be trendy on Instagram instead of waiting for next year. If I were to guess, the original finale of Eleven closing the gate, probably got cut and a few other scenes got truncated in the process to make the new finale fit. They probably chose such a low scale scene to put in the maze because it's probably the only one finished in time that they could watch before construction.
Next studio note is the scares in the first 1/3 of the maze. Last year's maze was oddly low on fright as well, and I think by design Uni wanted it that way so children aren't so terrified. They know kids are coming to experience this event just because of the show and the less complaints from pissed off parents, the better. A lot of people said this felt like a "walkthrough musuem" and that might be true considering Uni opened up their maze last year to be just that during the daytime and I bet they'll do the same this year. There's spots in the first 1/3 of the maze that are clearly made for scares. You can see spots clear as day ready to be utilized. Studio notes probably cut all scareactors because it was "too scary" and left the puppets since those were already made. Now that surveys are coming back saying the maze isn't scary enough, they're putting the originally intended scareactors back in.