Why?

As explained in #2728 group doesn't work with async functions (or execution).

This is not specific to group - anything that keeps state has problems with keeping that state in async execution.

This is more explored in the issue above and in this tc39 proposal.

What?

As the problem is so generic and was already kind of tried to be fixed for group in #2863 the point of this is to have a little bit mroe generic solution akin to the one in the tc39 proposal above.

This is a research task trying to make that possible and then make it possible to implement a group like API for async functions.

Probably after #2869 is also fixed.

The two issues though are orhogonal.

This can also be though of as continuation of #884