mysql 8 superslow with accounts transferred from older servers

So we have around 17 servers all with cpanel. However we setup a new server a week ago which obviously got mysql 8 and not mariadb installed on it. We then transfer some accounts over and immediately noticed extremely slow response times on wordpress sites. New installed sites are fine on the server but older ones transferred from older servers are not. We checked mysqladmin processlist and found tables were locked. After a week of troubleshooting we found the following to possibly be the cause. MYISAM tables dont work well with MySQL 8. Mariadb it does fine but not MySQL 8. So we made the default storage engine to MYISAM in my.cnf and suddenly sites are lightning fast again. Hope it stays that way and we will continue to monitor. But we may have to rather setup a new server with mariadb and moves all these customer accounts across again to resolve it completely.