Have not used it for programming.
At work, this is to some extent because we haven't decided yet whether to trust sending away our codebase to be potentially trained on.
In general, this is because I find the agressive FOMO-inducing marketting revolting, and because it would be increasing our dependence on big tech companies where I believe we should do just the opposite.
I did use it once or twice to get pointers on topics I wasn't familiar with (e.g., new standards or protocols, ...), mostly just to get a helicopter view and some sources to follow it up when i was in a rush at work. Would not do that on my personal time.
I wouldn't object to using an open-source/open-training, ethically trained, self hosted model.
There is actually a fair bit of drama around this relationship with Collabora, it would seem: https://community.documentfoundation.org/t/vote-revoke-votes-related-to-libreoffice-online-atticiziation-and-freezing-of-repository/13495