Card HTML, CSS Flexbox

Good job friend!!

Try including container your div's in landmarks or semantic HTML tags. This should solve the accessibilities issue of your work. For landmarks use this:

<div class="my-div" role="sectionmydiv"> </div> This should solve your issues.

Try comment your code also, which are signs of good practices (write meaningful comments).

Avoid styling the tag element itself, rather use a class for it. Which is also good practices.

Note The classes should be self descriptive.

Nice try but you have to revist your work. Image tags must have alt text <img src="./flower.jpg" alt="flower">. Also you can use background-size: cover; object-fit: cover; to make the image have a perfect fit. There need to be equal spacing between the heading, paragraph, and the stats. And all your content must be contained in a landmark. You can learn more about it here