for those following the recent spam-wave on #fediblock, and especially those trying to maintain lists for spam-affected instances, I want to suggest you take a look at #fediseer. It's a tool a deployed specifically for such use cases.
If you're maintaining a list, you get an interface (or can make your own integration) to add/remove instances from a public list. If you're trying to keep up to date, you can automatically follow someone else's list and update your silences. https://gui.fediseer.com