Limits are so low that I cancelled after about two weeks on my initial $0 trial. I tried making a change to a tiny code base with Claude Sonnet (which they offer in Antigravity). It couldn't even finish the change before my weekly limit was used up, reset in 7 days.
I tried the Anthropic models because gemini-pro had already been rate limited with a 5 day wait. I got some actual usage out of the Google model, but laughably little compared to what I got with ChatGPT Plus. This is definitely not an imagined thing from my side, you just have to look at the Antigravity forums: