SharePoint Framework v1.12.0 release notes
This release introduces a new property & event in the Web Part API to detect the rendering width (and changes), improved support for Microsoft Teams solutions, and updates supported versions of Node.js.
Released: March 15, 2021
Version 1.12 release is currently considered as deprecated and has been unpublished due the unexpected regressions.
We recommend usage of the updated version v1.12.1.