In 2020, Collier was criticised over the implementation of the Ofqual exam results algorithm which was termed by teachers and students as unfair for the purpose of grading the students following the cancellation of the GCE Advanced Level exams due to the COVID-19 pandemic. The algorithm used initially led to a downgrading of 40% of the A-Level results and was later removed. On 25 August 2020 she tendered her resignation from the position of chief regulator of Ofqual. She was later replaced by her predecessor as the chief regulator of Ofqual, Glenys Stacey, on an interim basis.