Users are already planning protest art. I personally wouldn't encourage people to join because it's more traffic for Reddit, but that's just me.
On other news, apparently requesting a subreddit now requires a 28d old account with 100+ karma.
EDIT: it's on again, since 20min ago:
The only two recognisable things are the "fuck spez" and nationalists spamming some government flag.
EDIT 2: better view:
I think that the meaning of the sentence in German up there should be rather obvious. It's on-topic.
Just make every pixel black.
Man I wish I had the reach to actually make that happen
There is a discord group called The Swarm that plans on doing that with 1,000 people. They also allied themselves with another group to put a protest message in the middle of it.
Link to the discord group? I still have a throwaway account over on RedditI used for a single post a few years back