CSS Image having border-bottom when I don't want to
Solution 1:
The cleanest solution would be to apply class to your a tag.
a.simple-link:hover {
border-bottom: 2px solid red;
}<div>
<a class="simple-link" href="">Link</a>
<img src="https://via.placeholder.com/150">
<a href="" class="nested-link">
<img src="https://via.placeholder.com/150">
</a>
</div>