D3.js graph not showing in mobile

I just found out that my d3.js graphs are not showing up on mobile.
Can someone please explain me?
My Codepen graph links:
ScatterPlot - https://codepen.io/mmmc-chrono/pen/eYKrWxm
Bar Chart - https://codepen.io/mmmc-chrono/pen/yLEvWRN

They show up fine for me (ie I open the link, the graphs are there). Can you be a bit more specific?

On my mobile, when I view it in CodePen I can see only see HTML footer element and freeCodeCamp test box.
But when I add
<script src="https://d3js.org/d3.v3.min.js" charset="utf-8"></script>
to the head element,
I can see my SVG title and SVG box but the rest within SVG are missing.

I changed the script’s src to https://d3js.org/d3.v7.min.js and I can see the graphs now.
If possible, can you please explain me why this happened and recommend me the most reliable websites for cdn link?
BTW, Thanking you for replying me!