Looks like the 20 file logic is present in neovim as well. I went through its code (https://github.com/github/copilot.vim/blob/release/copilot/d...) after beautifying it (https://codebeautify.org/jsviewer), and found it present.
I couldn't exactly trace it to a specific neovim event but I'm guessing it corresponds to buffer-update-events (https://neovim.io/doc/user/api.html#api-buffer-updates) or something like that.
Re: getting in trouble
I surely hope not :P. I mean, the code is basically public (available on every user's computer).