Changelog is included only in licensed SDK.
You can get the details of new and updated API from API documentation.
https://paramquery.com/pro/apiNew, updated API is labelled as new, updated, etc and breaking changes are mentioned in upgrade guide.
If you have to upgrade from v3, you would need to refer to all API and upgrade guides from v4 to v5.
New features are also demonstrated in demos section and labelled with
New.