I attended a VFX webinar session conducted by DNEG called #DNEGDeepDive a few weeks ago. They have since uploaded it online. Also on this page is an excerpt of the webinar i.e. the VFX breakdown of Brahmastra: Part One Shiva.
The session that was held by DNEG VFX Supervisors Jaykar Arudra, George Murphy, Alexander Seaman and ReDefine VFX Supervisor Viral Thakkar. They dive into creating the Astraverse and the challenges they faced, behind the scenes and much more.