Some Custom Domain project endpoints are currently signed by Let's Encrypt's cross-signed chain.
These endpoints will start being signed by Let's Encrypt self-signed chain starting the 9th of September, 2024. For additional details, please refer to Cloudflare's documentation for this change.
The primary impact of this will be to disrupt traffic from extremely old systems (e.g. Android =< 7.0) that trust the cross-signed chain, but not the self-signed one.
If you are impacted by this, please reach out to https://supabase.help and we can help you migrate to an alternative CA.