In a world of explosive amount of content about AI and where NOT having an AI newsletter has become a rarity there are a few authors and sites I like to read for their more thoughtful and long form content:
https://gwern.net/#deep-learning (also has a great darknet markets series of articles)
https://ym2132.github.io/ (primarily long form posts about GAN)
https://simonwillison.net/ (python + AI)
https://retrochronic.com/ (AI + philosophy)
And a bonus for the video inclined - AI explained youtube channel
I might add or update this in the future.