The posts are intended to highlight racial injustice as well as giving attention to black voices that might otherwise not be heard.
But some users have pointed out that the posts are in fact filling up useful hashtags and stopping people from getting the information they need.
The event, known as "Blackout Tuesday", began in the music industry as a protest against ongoing police brutality. Those supporting the event suggested it would be "a day to disconnect from work and reconnect with our community" and suggested using the hashtag "#THESHOWMUSTBEPAUSED".
But it has quickly spread to other users too, with a variety of major brand accounts as well as individuals posting black images to show that they are supporting the protest.
Feeds are then not supposed to post through Tuesday, leaving the blacked out image at the top of their profiles.
In that way it is similar in aim to the "#AmplifyMelanatedVoicesChallenge" that has spread quickly across a variety of social networks. As part of that movement, white users are asked not to post on their feeds, and instead use the time to read and reshare content from people of colour.
Numerous users pointed out that the blackout posts were appearing in the feed for #BlackLivesMatter, potentially getting in the way of useful information being shared on the same hashtag. Numerous users asked people posting the blackout image to reconsider using those popular hashtags in their posts.
Those posting on the Black Lives Matter hashtag on Instagram have also run into issues with an error that shows an "action blocked" message and stops them from posting. Instagram has said the issue was because of its anti-spam technology, and that it is working to fix it.
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