This thread is worth reading if you are a Google docs user.
Short version: When you export a document from Google Docs, Google replaces all your hyperlinks with links that allows Google to monitor the interactions of everyone you share your document with.
This hidden link replacement can potentially be used to build a model of your professional relations, where people who interact more with your content are considered a stronger relation.
Think about the implications.
https://fosstodon.org/@Joe_0237/111145684757912952