HMRC have said that it will be concentrating their CJRS compliance activity on those who have been abusing the system. It will focus on fraudulent claims and not on cases where the employer has made an innocent error. The first compliance letters began to arrive on 18 August. Have your cleints received such a letter?
I would be interested to see a copy of the letter, if you can provide a redacted copy, as HMRC has not shared the text with the professional bodies.