1015: You are being rate limited
Likely cause
A Cloudflare rate limiting rule (or your origin's own rate limiting) is blocking further requests from this client due to request volume.
Check
In the Cloudflare dashboard, go to Security > WAF > Rate limiting rules and look for a rule matching this traffic pattern.
Fix
Adjust the rule's threshold, or add an exception for this legitimate traffic pattern (e.g. an allowlisted IP or user agent).
Verify
Wait for the rate-limit window to reset, or after adjusting the rule, retry the request.