Employment visa question

Hi folks, I'd be grateful for any advice/experience you may have on this, if someone previously resigned from a job but their employment visa has not expired yet, according to the website Hong Kong Visa Geeza this gives that person the privilege to stay in HK and look for another job until the expiry. However, according to ChatGPT, this is not the case and theoretically that person needs to notify the Immigration Department and leave HK as they no longer have an employment visa.

If that person then finds another job, but it has been some time between the resignation and the new job opportunity, for example it's been one year of unemployment, then would it be accurate to say the new employer would have to do an employment visa sponsorship as a new employment visa? As a change in visa sponsor appears to only be it the transfer between jobs is relatively closer in time (for example, leaving the previous job for the new job). Am I correct in that understanding?

Would really appreciate any information you guys are happy to share! Thank you!