Can't set default value of DATETIME column

[baptistemarchand]

During the upgrade process, one of the SQL statements I have to run is this one:

ALTER TABLE `MedicalTransporter` CHANGE `lastBookingRequestAt` `lastBookingRequestAt` MEDIUMTEXT NOT NULL DEFAULT '1970-01-01T00:00:00Z'

But when I run it (in Sequel Pro) I get this message:

BLOB, TEXT, GEOMETRY or JSON column 'lastBookingRequestAt' can't have a default value

Even though this column as type DATETIME

I'm using MySql 5.7.28. Not sure if that's a MySql issue or something Prisma can handle.