After George Floyd's death in May 2020, the volume of discussion in social media increased dramatically. A series of protests followed this tragic event, called as the 2020 BlackLivesMatter movement. Eventually, many user accounts are deleted by their owners or suspended due to violating the rules of social media platforms. In this study, we analyze what happened in Twitter before and after the event triggers with respect to deleted and suspended users. We create a novel dataset that includes approximately 500k users sharing 20m tweets, half of whom actively participated in the 2020 BlackLivesMatter discussion, but some of them were deleted or suspended later. We particularly examine the factors for undesirable behavior in terms of spamming, negative language, hate speech, and misinformation spread. We find that the users who participated to the 2020 BlackLivesMatter discussion have more negative and undesirable tweets, compared to the users who did not. Furthermore, the number of new accounts in Twitter increased significantly after the trigger event occurred, yet new users are more oriented to have undesirable tweets, compared to old ones.