I was looking to find all of Confluent's docker images, but the linked DockerHub page is returning a 404 error:
https://hub.docker.com/u/confluentinc/

This was a Docker Hub bug -- it looked like they were 404ing for any organization if you weren't logged in and a member of the organization. It appears to be fixed now. I'm going to close, but feel free to re-open if you are still seeing the issue.
There is some regression?
Today I had exactly the same issue. I left my computer on the whole day. Every docker hub page like https://hub.docker.com/_/mariadb ended in 404 error pages.
I pressed "sign in" and immediatly was logged in (no login form). I was trying to reproduce this issue by logging off but the everything worked as expected. So there still is some issue when your cookie expires!?
Most helpful comment
There is some regression?
Today I had exactly the same issue. I left my computer on the whole day. Every docker hub page like https://hub.docker.com/_/mariadb ended in 404 error pages.
I pressed "sign in" and immediatly was logged in (no login form). I was trying to reproduce this issue by logging off but the everything worked as expected. So there still is some issue when your cookie expires!?