You must have some git plugin I haven’t heard about.

Git blame will show the commit and the date for each line. It’s easy to verify if the snippet has changed since the comment. i use Emacs and it’s builtin vc package that color code each block.

But you need the snippet and, potentially, the entire call tree (both up and down).

And anything that can affect relevant state, any dependencies that may have changed, validations to input that may have been modified; it’s hard to know without knowing what assumptions the assertion is based on.