We are using Akamai in front of our Opti app which is configured with True-Client-IP header. On the Opti side, this site is configured to use Cloudflare as the origin, with WAF disabled. Opti cloudflare is only seeing Akamai edge server IP addresses in their logs which is not helpful. Akamai is sending the actual client IP address in the header, but support cannot configure Cloudflare to see it. The following process should allow Cloudflare to see it:
You can configure Cloudflare to log the True-Client-IP header instead of the Akamai edge server IP address by enabling the “Add True-Client-IP Header” Managed Transform. This will add the True-Client-IP header to all requests to your origin server, which includes the end user’s IP address. You can then retrieve this information from the True-Client-IP header.

To enable the “Add True-Client-IP Header” Managed Transform, follow these steps:

Log in to your Cloudflare account and go to the “Transform Rules” tab.
Click on “Managed Transforms” and search for “Add True-Client-IP Header”.
Click on the “Add True-Client-IP Header” transform and click “Enable”.
Once you’ve enabled the transform, Cloudflare will start adding the True-Client-IP header to all requests to your origin server. You can then configure your logging to capture this header and log the true client IP address instead of the Akamai edge server IP address.

Note that this feature is only available on Enterprise plans. If you’re on a lower plan, you may need to upgrade to Enterprise to access this feature.

Source: https://developers.cloudflare.com/network/true

Sources:
https://developers.cloudflare.com/support/troubleshooting/restoring-visitor-ips/restoring-original-visitor-ips/
Additional resources
DNS records that should be proxied