I am trying to upload an ssl cert and key to create a custom subdomain with Zoom Events and this is the error message they give me - [Cloudflare] the certificate that you uploaded is having trouble bundling against the public trust store - unable to upload a certificate_pack: unable to bundle certificate: cfssl: request failed: reject certificate issued by CF origin CA (1200). Please check your input and try again
You should always use Full (strict) or you won’t be secure. That won’t fix this problem, though.
The Cloudflare Origin CA is only trusted by Cloudflare. The error message suggests that Zoom needs you to provide a certificate issued by a publicly trusted CA. I’m surprised that they don’t provide an automated solution using one of the free ACME enabled CAs.
You will need to confirm the certificate requirements with Zoom and provide them with a compatible certificate.