Hifihedgehog As the GitHub roadmap states,
A last big batch of code restructurings, most of them in the backend. This is mostly interesting to extension developers, as most (or probably all) existing extensions will be affected. On the bright side, they will benefit from new stability guarantees with the newly introduced APIs.
The new documentation, which will be part of the beta 8 release, will have a changelog of the things changed in beta 8 from beta 7 and also more documentation for extension development that should help.