Cloudflare workers erratically slow / GB-sec never resets!

Dear community,

I am using a cloudflare worker to act as a reverse caching proxy over S3 resources for a website.
About 20 queries are needed to load a typical website page, less than 1MB (that’s not the point, just some more context).

It used to works beautifully for a few days but now it does: about ~5 requests at full speed, ~5 requests > 10 sec, ~5 requests > 60 sec, ~5 requests returning 500, 520 or 524 errors. The patterns remains relatively stable but the page having the errors or slowness are not always the same…

I am using the free plan. Is there a way to see if any rate limit apply ?

I have used about 400 requests today, median cpu time is 0.9ms. The execution duration seems to keep growing currently hitting 172GB-sec. I am a bit unsure how and when it should reset, I have the impression it steadily increased every day.

I cleared the cache, deleted and redeployed the worker with no change in the observed broken behavior.

Thanks a lot for taking the time to read and respond.

Adding that I verified that the S3 server is not applying any rate limits on its side.