When you work on proprietary code with a lot of trade secrets contained in it, on a codebase that did cost millions of dollars of man-hours to build and that holds the company's IP, you tend to be very careful where you're sending that to.
If you think your codebase is your competitive advantage or trade secret, you're in for bad time. AI coding has made code cheap it's the least valuable part of the value add for most companies. Almost any software company can easily be replicated with a few AI prompts. The real proprietary value is in the marketing distribution partnerships and data, not code.
I don't think any AI company meets the bar you are setting here.
Why would anyone working on such code send it anywhere (other than, say, to AWS for hosting)?
Source: I work on such code. We don't allow devs to use (cloud-based) LLMs.