Guideline (EU) 2020/978 of the European Central Bank of 25 June 2020 on the exercise of the discretion under Article 178(2)(d) of Regulation (EU) No 575/2013 of the European Parliament and of the Council by national competent authorities in relation to less significant institutions with regard to the threshold for assessing the materiality of credit obligations past due (ECB/2020/32)