How can ToolJet relicense AGPL contributions to a less restrictive license?

The code is AGPL and accepts volunteer contributions under that license.

https://github.com/ToolJet/ToolJet/blob/develop/CONTRIBUTING...

However, in their AGPL announcement it says:

> We do have a commercial license that overrides the AGPL license. This commercial license allows organizations to make changes to ToolJet and provide it as a service.

https://blog.tooljet.com/changing-license-to-agpl/#what-some...

Does the hosted ToolJet service include unreleased code, leveraging this commercial license?

Every volunteer contributor would need to agree to relicensing and/or would need to have previously agreed to assign their copyright to ToolJet, right?