Can Microsoft JDBC Driver 4.0 connect to SQL Server 2019 and perform DML without issue?
Microsoft and my testing have confirmed that JDBC drivers not marked as compatible in the SQL version compatibility matrix might connect to a non compatible version of SQL Server and continue to work without issue.
 
However, there is no guarantee that all functionality detailed in the Driver feature support matrix for Microsoft SQL Server is supported. They also only test the  driver versions marked as compatible against the stated version of SQL Server.
JDBC version 4.0 was not specifically tested.