It remains to be established if Google performed the policy due to ethical concerns or rampant abuse of the free computing resources utilised by these projects.
Colab is meant to be used by researchers who need power that costs several thousands of USD to help them reach scientific goals. That is especially critical during times of GPU shortages.
Instead, there are reports that some users are exploiting the platform’s free tier to create deepfake models at scale. This captured a significant amount of Colab’s available resources for extended periods.
While some projects could fit in that context, it appears that Google has detected far more abusive than legitimate cases.