If you had enabled the option for your tweets to automatically get published on your Facebook timeline, then all of them are going to be scrubbed. Facebook is opting out of Twitter cross posting and erasing all the old posts that users made on their timelines from Twitter. The reason being the privacy oriented restrictions with the API for third party developers.
The new restrictions come in the light of Cambridge Analytica data privacy scandal. Personal information of over 87 million users were sold to a data mining company that disturbed the company in March. Following these events, Facebook has disabled the ability for third party apps to post on behalf of a user. In fact, the third party apps can not interact directly with user’s profile.
On August 1, the restrictions came into action. But it is observed that not only Facebook has disabled the ability to interact directly but also scrubbed off all the old posts that were cross published from third party apps like Twitter.
However, only a few handful of people are affected by obsolescence of this feature, and even smaller number of people are complaining about it; that too on Twitter. The feature was godsend for those less active users who would like dodge the nuances of social media and prefer to post on only one website. Maybe that is why the change is not converting to a noticeable outcry.
Facebook has not notified the way in which the changes take place, nor there appears any public documentation of company’s post removal action.