You are using Elementor Canvas which strips all of GP’s elements and style so I wonder if they would have a better method for this instead of us giving you CSS solution to modify it.
I think it’s worth checking with their support.
Otherwise give this a shot:
.post-template-elementor_canvas.single elementor-container a {
text-decoration: none;
border-bottom: 1px dotted red;
}
But again I would recommend checking with their support as you can see the CSS is targeting their content.