What you mean? They're right. The content creator has to interact with Gemini to summarise the comments and only then a message would show which could contain a link, to the content creator.
The comment's author has no way of extract data from the content creator just by being leaving a comment. They content creator has click a link that the summarisation shown (likely removed by Youtube because it already doesn't allow clickable links in comments).
This is a prompt injection to include a malicious link in the response. The user would still have to click that link.
I think Google should put in some effort to avoid this type of low-effort prompt injection, but it also does require a second step of users clicking the malicious link in the AI output.
The comment's author has no way of extract data from the content creator just by being leaving a comment. They content creator has click a link that the summarisation shown (likely removed by Youtube because it already doesn't allow clickable links in comments).