Yarn 2 aka berry stable version was released in January 2020.
Yarn 1 will be in maintenance mode only.
Yarn 2 is rewritten from scratch and has extended support for workspaces, its plugin architecture has benefits for tools such lerna.
There is good summary of yarn 2 features in article by one of the yarn authors. Lerna is mentioned more times.

Do you have any plans with lerna related to new yarn? Maybe some yarn 2 plugin? Maybe as another project? Will be yarn 2 supported with lerna?