>This seems to be a big change in the requirements it seems

How is that a big change and what requirements are you talking about?

The Javadoc of the @Column annotation clearly says that precision is only supported for decimal/numeric types and that the unit is decimal digits. Providing a precision for float/double types is “unspecified“. So far, Hibernate 5 just ignored the value you have been providing.

Hibernate 6 now interprets this as decimal digits, just like for decimal/numeric types. It translates the value you provide to the binary digit precision by calculating decimal_precision*ln(10)/ln(2).