You're confusing two separate issues: patents and the licensing of those patents.
AV1 is not "patent free" at all. There are plenty of patents that pertain to AV1 owned by the Alliance for Open Media. AOMedia gives you a patent license to use AV1 royalty-free:
https://aomedia.org/license/patent-license/
https://aomedia.org/press%20releases/the-alliance-for-open-m...
What's happening separately is that patent licensing organizations are forming their own patent pools in an attempt to seek rent from existing and future AV1 users. Their claim is that they have patents essential to AV1 and you must pay them a licensing fee.
Sisvel is trying it on: https://www.sisvel.com/licensing-programmes/audio-and-video-...
And so is Avanci: https://www.avanci.com/video/
They characterize this is as providing AV1 implementers the "opportunity" to minimize the risk of being sued:
https://www.streamingmedia.com/Articles/ReadArticle.aspx?Art...
These grubby patent pool organizations are the practical reason why it's better to stick with royalty-free formats and protocols on the internet.
And why more work must to go into making sure internet audio and video formats are and remain royalty-free.