We have a costume made CRM, but we are facing some issues with the queries. Suddenly they become slow. We guess we had and upgrade on the server which affect all. We are using MySQL 5.7.36 and we disable Group By on sql_mode. We know that the problem is on Group By, but we can't fix it. Our server is 64 GB RAM 16 Core running con Cloudlinux. We are looking for an expert on the field who can help us.