What Happens to Relicensed Open Source Projects and Their Forks?

A Linux Foundation project focused on understanding the health of the open source community just studied the outcomes for three projects that switched to "more restrictive" licenses and then faced community forks.
The data science director for the project — known as Community Health Analytics in Open Source Software (or CHAOSS) — is also an OpenUK board member, and describes the outcomes for OpenSearch, Redis with fork Valkey, and Terraform:
The relicensed project (Redis) had signifi