> Although utf8 is currently an alias for utf8mb3, at some point utf8 will become a reference to utf8mb4. To avoid ambiguity about the meaning of utf8, consider specifying utf8mb4 explicitly for character set references instead of utf8.

https://dev.mysql.com/doc/refman/8.0/en/charset-unicode-utf8...

Can't fault a database vendor being conservative, but looks like this is planned. Maybe this will be a 9.0 thing.