MySQL 8.0 Release Notes
MySQL 8.0 Source Code Documentation
By default, MySQL 8.0 rejects invalid or improper data values and aborts the statement in which they occur. It is possible to alter this behavior to be more forgiving of invalid values, such that the server coerces them to valid ones for data entry, by disabling strict SQL mode (see Section 5.1.11, “Server SQL Modes”), but this is not recommended.
Older versions of MySQL employed the forgiving behavior by default; for a description of this behavior, see Constraints on Invalid Data.