http://markdown-it.github.io/#md3=%7B%22source%22%3A%22%23%20Issue%20579%5Cn%5Cn!%5Btext%20%3Ctextarea%3E%20text%5D%28image.png%29%5Cn%22%2C%22defaults%22%3A%7B%22html%22%3Atrue%2C%22xhtmlOut%22%3Afalse%2C%22breaks%22%3Afalse%2C%22langPrefix%22%3A%22language-%22%2C%22linkify%22%3Atrue%2C%22typographer%22%3Atrue%2C%22_highlight%22%3Atrue%2C%22_strict%22%3Afalse%2C%22_view%22%3A%22src%22%7D%7D

Currently, any HTML tags are swallowed. The spec is a little light https://spec.commonmark.org/0.30/#images but recommends that the string not be parsed.

See how GitHub will render the raw string:

Ref DavidAnson/markdownlint#579