acheong08 has just archived his project. I don't know if it is related or not.
There are solutions that allow one to use GPT-3.5 by abstracting away the UI but still using one's ChatGPT account. On OpenAI's, side, that probably appears as the user making normal prompts from the default UI.
The big issue with using public APIs, even when they are advertised as free is that it defeats their purpose and thus makes the investment worthless for them. OpenAI models are not free, nor is the computing power they use for inference. Whenever you see any of them used anywhere, someone had to pay and they did it because they had interests. For instance, Bing includes access to GPT-4 (with 2000 characters limit) for "free" while ChatGPT Plus users pay to access the same model. The same goes for Dall-e which can also be used for "free" via Bing while regular access is paid. Their goal is to become a dominant search engine and defeat Google. They also want Edge to surpass Chrome in browser market shares. They know that if they achieve that, they will have at least hundred of billions of new revenue. That is why they are willing to invest billions in research and daily upkeep of these models. ChatGPT was a way for them to get massive user feedback and real-life human conversations to improve their models, that is why it was given to the public for "free" and also why they still have a free tier. All other services that give access to GPT-4 do so in order to increase their user base and further their bottom line.
When you create indirect access to their service, you destroy their business model as they support those APIs but will not get the expected return.

I think the case of a restaurant might be a befitting analogy. A restaurant is a public place, you can come in to meet people and talk with them. You can order water which is free, sit on their chairs and use their space. However, if you don't order anything else, they don't make money off of you. If most people come in, do that, and leave, they won't be able to support their staff, pay their rent and keep the place clean and welcoming. That is why waiters will keep prompting you to order something, and if they find out that you have no intention to order anything paid, they might even kick you out and you can't rightfully blame them just because it is a public place.
Likewise, when the companies who own those apis find out about this project, I envision them having the same reaction: "Let's shut that down A.S.A.P.".

At least, that is my understanding of the situation. Also, I remember the case of Faker.js from last year that showed us clearly that we don't actually own any of the code we upload to GitHub, no matter which License terms are in a repository. Of course, Marak did not handle things ethically but what GitHub did set a clear precedent. If they don't like the way a repository is handled, they can simply take it and do as they please, they can even exclude you from a project you started and worked on for years. Considering that Microsoft owns GitHub and OpenAI, I won't be surprised to come back tomorrow and see that this repository has just disappeared without explanations given to you or anyone else.