Rant about the concept of open source freeloaders: there's no such thing as open source freeloaders. If the license explicitly gives you the right to use the stuff for free, there's nothing wrong in using this right. While it would be the right thing to give money / otherwise support the projects you rely on, it's on the software developers who decide to give these rights (I also think it's the right thing to do though) to figure out the business model.
There's also nothing wrong in being upset about something you relied on disappearing overnight. If someone decides to provide something for free, they should give time for people to stop relying on this free stuff if they can.
However, I also believe you should own it if you decide to ever rely on prebuilt Docker images. More specifically, if you are relying on prebuilt Docker images, you are letting someone else decide on a part of your infra. And yes, this someone else can decide to stop providing this part of your infra overnight. This is on you.
I also don't find anything wrong in deciding to not provide binaries for your open source project, or to stop providing binaries, including docker images.