Illegal knee UFC 259: Why was Petr Yan’s knee illegal during Bantamweight Championship match against Ajimain Sterling?

Illegal knee UFC 259: Why was Petr Yan’s knee illegal during Bantamweight Championship match against Ajimain Sterling? The title changed hands on a disqualification. Ajimain Sterling has prised the Bantamweight Championship from Petr Yan under unusual circumstances. During their match…