You should be able to see the challenged or blocked event under the Security tab → Events at Cloudflare dashboard for your zone and know exactly which security option was triggered. Could be Managed Rules my best guess, otherwise Bot Fight Mode or Browser Integrity Check.
Once you find them, click on a particular one to find more details about it (user-agent, IP, HTTP version …). If yes, could you share some details which service was triggered that blocked you?
you should see your origin host/server IP out there and user-agent like WP-cron or WordPress/version
Just in case if you encouter some issues and/or errors, since it’s related to the WordPress, I’d suggest you to allowlist your origin host / server / hosting IP address by navigating to the Security → WAF → Tools → IP Access Rules with the action “allow” for your Website and try again.
It knows to happen due to the WordPress using HTTP/1.0 and empty user-agent, therefore while executing WP-Cron or some other related JSON/REST API request via plugin which triggers the WAF rules (as it should normally).