mihaic195 said almost 2 years ago on Active Storage Uploads Behind a CDN :
Based on the Rails Documentation from https://api.rubyonrails.org/classes/ActiveStorage/Variant.html
all I had to do is call processed on the image to create the variant, which is still weird to me. Now the CDN link also works.
Thank you!

<%= image_tag cdn_url(@user.avatar.variant(resize_to_limit: [100, 100]).processed)