Starting with MySQL 8.0.20 it supports a new syntax for INSERT ON DUPLICATE KEY UPDATE to refer the new entry in the insert statement:
docu

They use the AS keyword to refer to the new entries instead of using VALUE[S]()
INSERT INTO t1 (a,b,c) VALUES (1,2,3),(4,5,6) AS new
ON DUPLICATE KEY UPDATE c = new.a+new.b;