If you've used Twitter in the last six months or so, you'll have seen serious and obvious bugs.
Large numbers of people report seeing a bug. Having them all be liars seems rather unlikely.
Seeing bugs is one thing (I stopped using twitter like 5 years ago or so and it was always a bug fest so I can believe it got even worse) but we are talking about a single specific bug here with important privacy consequences. Some reliable proof would be nice.