Why does my query take over 30 mins on MySQL 5.7 but a couple seconds on MySQL 8?

I have the following query. On MySQL 5.7 it takes over 30 mins minutes to run but on MySQL 8 it takes less than 10 seconds. There are around 20k records in students_t, 500 in classes_t and 1100 in groups_t. student_enrolled_classes_t contains 100288 records and 160156 records.There are no foreign keys in place.

SELECT DISTINCT
       s.forename
     , s.surname
     , count(c.id) as 'classes'
     , group_concat(DISTINCT g.name) 'groups'
  FROM students_t s
     , student_enrolled_classes_t c
     , student_enrolled_groups_t eg
     , groups_t g
 WHERE s.id = c.student_id
   AND s.id = eg.student_id
   AND eg.group_id = g.id
GROUP BY s.id, c.id
ORDER BY s.forename ASC;

The table structures are (generated with Hibernate):

CREATE TABLE classes_t 
(id BIGINT auto_increment PRIMARY KEY);

CREATE TABLE groups_t 
(id BIGINT auto_increment PRIMARY KEY
,name VARCHAR(255) NULL);

CREATE TABLE student_enrolled_classes_t
(id BIGINT auto_increment PRIMARY KEY
,class_id BIGINT NULL
,student_id BIGINT NULL);

CREATE TABLE student_enrolled_groups_t
(id BIGINT NOT NULL PRIMARY KEY
,group_id BIGINT NULL
,student_id BIGINT NULL);

CREATE TABLE students_t
(id BIGINT auto_increment PRIMARY KEY
,forename VARCHAR(255) NULL
,surname  VARCHAR(255) NULL);

Thank you