Laura Loomer was banned from Twitter for claiming that Ilhan Omar was anti-semetic (more specifically she called him "anti Jewish") in November of 2018. Beyond this, Laura Loomer also said that Ilhan Omar was part of a religion where women were being mistreated and abused as well as claiming they oppress indivudals who were gay.
Loomer also claimed that the members of that religion are being made to wear a hijab. This is considered hate speech as well as an attack on Ilhan Omar's character and religious beliefs. This violated Twitter's rules and so she was banned.