Good question! By and large, some of the following would count as a "strike":
Poor moderation
Excessive spam
Most importantly: Making non-backwards compatible changes to the ActivityPub specification that may lead to the classic "Embrace, extend, extinguish" situation
Kbin.cafe on Blocking Meta's New Threads App (kbin.cafe)
For those who aren't aware, Kbin Cafe is a Kbin instance I run. Cross-posting our stance on Threads for visibility....