Commented by: @mrotteveel

This is an intentional change with the ResultSetMetaData that was introduced in Jaybird 2.2.0 to be compliant with the JDBC specification. See the releasenotes: http://www.firebirdsql.org/file/documentation/drivers_documentation/java/2.2.5/release_notes.html#__RefHeading__3644_1575618738 and http://www.firebirdsql.org/file/documentation/drivers_documentation/java/2.2.5/release_notes.html#__RefHeading__3722_2133805793

"FBResultSetMetaData#⁠getcolumnName(int) will now return the original column name (if available) for compliance with the JDBC specification, getColumnLabel(int) will still return the alias (or the column name if no alias is defined). See Compatibility with com.sun.rowset.* for potential problems when using the reference implementation of CachedRowSet.
Jaybird 2.2.1 introduced the connection property columnLabelForName which will revert to the old behavior when set to true. Be aware that the old behavior is not JDBCcompliant."

Historically JDBC wasn't entirely clear on the distinction between name and label, but it has since been clarified.. getColumnName is supposed to return the original column name (if any), if you want the alias then you need to use getColumnLabel (the label is also what you should use when retrieving values from the ResultSet by name).

If you want the old behavior (which is not JDBCcompliant), then you can specify the connection property columnLabelForName=true. I'd strongly advise to fix your code instead of relying on the old and incorrect behavior, and only use the columnLabelForName property if you depend on third-party tools or applications that need the old behavior.

Commented by: @mrotteveel

Closing as "won't fix" as the behavior is intended, and a workaround is available (see JDBC260)