How ignore 'cert issues' in Workers subrequests?

We have a public service, CDN Finder, that enables you to quickly see which CDN a site is using.
CDN Finder runs entirely in Workers.

We’re seeing 526 and 525 responses for subrequests, for URLs that load fine in the browser.
Example:
https://community.windows.com

The first thing CDN Finder does is fetch the URL and that subrequest fetch gets a 526 error.
Example CDN Finder result (JSON):
https://api.cdnplanet.com/tools/results?source=website&service=cdnfinder&id=1390136929795_894b5b9b0868a1376356

The SSL Checker on SSL Shopper shows no intermediate cert is present.
https://www.sslshopper.com/ssl-checker.html#hostname=community.windows.com

Our SSL/TLS encryption mode is Full.

The SSL/TLS tab in the dashboard states for the Full mode:

Full SSL: Your origin supports HTTPS, but the certificate installed does not match your domain or is self-signed. Cloudflare will connect to your origin over HTTPS, but will not validate the certificate.

From what we observe in our Worker for CDN Finder, Cloudflare does validate the origin cert.

Is there a way to have the Worker not validate the cert for subrequests?
Ideally, this is a Fetch request property.