[Feature]: Migration from v2 to v3

[IvanSavoskin]

Is your feature request related to a problem? Please describe.

Hi!
When upgrading from version 2.x to version 3.x, there were many fundamental changes that require rewriting some of the code and make the current project unworkable. Will there be some kind of migration guide? And if so, is there any time frame?
Perhaps it already exists somewhere, but I just couldn't find a full description of the changes in either the documentation or the patch notes

Describe the solution you'd like

The appearance of descriptions of all changes or a full migration guide

Describe alternatives you've considered

No response

Additional context

No response