Worker request limiting to avoid denial of wallet attack


Is there a way to limit worker global requests rate ?

I only see request limiting per IP in the WAF, but no total request limiting
Something like this exist in AWS Api Gateway (request throttling)

If a CF worker is attacked by a DDOS http request flood,
with 10k different IPs, each at rate of 1 request per second, this represents 26 billion request at the end of month, that will be billed 12960 dollars!

It looks those attacked are not always automatically blocked by CF, and
billed, if i read this message : Under sustained bot attack - Cloudflare Worker Site. Afraid of additional billing - #47