What you are seeing is Cloudflare’s abuse protection for Workers kicking in, as you are receiving thousand(s) of requests per second to a Cloudflare Worker.
Cloudflare’s abuse protection methods do not affect well-intentioned traffic. However, if you send many thousands of requests per second from a small number of client IP addresses, you can inadvertently trigger Cloudflare’s abuse protection. If you expect to receive
1015 errors in response to traffic or expect your application to incur these errors, contact Cloudflare to increase your limit.
So you will have to just create a support ticket and request Cloudflare support to increase that limit for you.