Am I limited to computer science only? Can it be in any technical field like computer engineering, data science, (quite possibly) Cybersecurity?
There is a good chance you could do another subject such as the ones you list and transition to AI. Data science is especially connected to AI/ML. However, that would only be half the battle: a degree in technical subject (specifically one with a heavy maths component) would be good evidence you are are potentially capable of doing AI/machine learning, since there is a lot of overlap with the required sort of skills, but still, having maths and technical skills doesn't mean you automatically have all sorts of AI and ML knowledge.
For example, I myself have a BSc in computer science and a PhD in machine learning. But when I look at machine learning jobs I frequently see jobs I am not capable of. I have literally spent the past 5 or 6 years learning exclusively about machine learning to a high level and while there are certainly plenty of jobs I could comfortably do, there is still a shitload I still couldn't do. ML is a massive field, there are dozens of different techniques and each technique has a dozen variants. Then there are lots of thinks to be skilled at beyond the raw ML algorithms (e.g. feature engineering, data mining, statistical analysis etc.).
Frankly, even if you did have a Bachelor's in CS, you would likely be unprepared for the vast majority of AI/ML jobs, unless your Bachelor's was tailored to specifically teach you all about AI/ML. Computer science is a gigantic field and most of what you learn during a CS degree isn't (directly) connected to AI/ML. In fact, you could go your entire degree and learn nothing about AI/ML - if your choice of courses to study didn't include any AI stuff.
For this reason, don't assume that just because you have a degree in a technical field you will gain access to all kinds of AI/ML jobs. I would say that normally you would need both an undergraduate and a postgraduate degree in a technical field - ideally computer science or maths, but maybe others are fine too (e.g. data science) - and it would be beneficial if you have a portfolio to showcase your skills in the form of personal projects etc.
Getting into the field of ML is not easy.