Hundreds - if not thousands - of Twitter users are reporting seeing tweets from people they don't follow in their timelines, and are justifiably asking for an explanation as to what's going on.
Whyyy am I seeing tweets from people I don't follow :s- N. (@natxnat__) January 11, 2017
Why are random tweets from people I don't even follow showing up on my TL- Laylow (@leyloandstitch) January 11, 2017
Why are there strangers on my timeline who I don't even follow- Angelo (@angelo_f1) January 11, 2017
If you too are seeing random tweets from random users in your timeline, don't panic - Twitter has acknowledged the problem and is working on a fix.
As reported by BuzzFeed, the issue relates to the 'You might like...' recommendations that Twitter adds to users timelines as suggestions on other accounts you might want to follow. Normally, those recommendations appear in a separate box to clearly single them out from your regular tweets, but due to a bug, those tweets are showing up in regular timelines with no indication as to why you're seeing content from those accounts.
How Twitter's 'you might like' recommendations should look
Twitter's told BuzzFeed the issue has been fixed, but reports are still coming through. But rest assured, if you are seeing random tweets from random users, it is an error and Twitter is working on a fix.