Is there any proof that the lower budget for this movie is impacting on the visual effects? According to this website (https://www.artofvfx.com/bumblebee/) and IMDB the VFX is being handled by ILM and some other studios that aren’t sub-standard.

The non-Cybertron scenes look fine to me. Maybe the Cybertron scenes look cartoony because G1 cartoon and toy designs look like crap when directly translated into real life. I’m pretty sure this is one reason why we ended up with the Bayformers designs.

I imagine the lower budget is more to do with a smaller scale movie with lesser known actors and only a handful of set pieces.