I just realized a couple of days ago that we now have limited free access to Chat GPT4: a certain amount of free questions every day is allowed until our quota is reached. Said quota is unspecified and depends on traffic on the server.
I also noticed that GPT4 has been improved compared to GPT3.5 which is much dumber and has a tendency to "hallucinate" a little more. It also seems GPT4 has real-time access to the internet as opposed to 3.5 which did not (I don't know if it does now). I guess it was designed on purpose so that people would be encouraged to pay for the better version... which is expensive and not unlimited; there are still quotas.
Recently I've been using GPT4 as a complementary tool to learn Mandarin such as making a weekly plan, translating words, grammar rules, expression meaning, explaining cultural context, etc. Overall, it's quite helpful