Idea

Some servers are known to "block" NCR, be it via direct or indirect detection measures. While implementation of #255 will provide a blanket solution to work around that, having a manually curated blacklist of such servers will allow much more specific and effective countermeasures, among which I envision dedicated warning screen when entering them and enforcement of particular signing settings. Users can be provided with convenient means to report offending servers.

Reasoning

In my mind NCR should be a nice-to-have-by-default thing for any client, which does useful work in the background even if you don't paricularly care about how it's configured or safety of particular servers. Possibility of being banned for simply having it installed directly subverts that goal, so it's worth counteracting in every way possible.

Other Information

No response

Mojang collaborated with GamerSafer to create a new official Minecraft server list. https://www.minecraft.net/en-us/article/the-official-minecraft-server-list-live

In there, the "Beacon of Safety Badge" indicates chat reporting.

Therefore, that list could be used in NCR to populate the blacklist fairly easily. Maybe they even have an API? Edit: yes, they do
Though right now it is notable that none of the Java servers have the badge, presumably because the badge also requires manual review.