worker runs request that goes into different subdomain

[sullen aspen]

I have relatively simple worker - for proxying and caching. It was setup to replace old system.

• let's say it's on domain staging.x.ltd (this domain in CF is cached and pointing to our legacy system in dns record)
• worker for most types of request it works and proxies requests mostly to prod.x.ltd domain (new system to replace legacy)
• somehow for some requests like to /api/auth/callback/google I'm receiving response from legacy system
  in worker logs I'm printing headers and url it passes to proxy - they all are ok - pointing to prod.x.ltd
  but response I'm getting from legacy and even cached
  age: '1090',
  'cache-control': 'public, max-age=300',
  'cf-cache-status': 'HIT',
  'cf-ray': '9ac5e3e7143ccbfe-WAW',

could someone help me looking into that?
Or - when, if I have worker on domain, I can get response from origin even though I see worker was run?

[sullen aspen]

I think I got it. When on subdomain subdomain STAGING in worker I was executing fetch to domain PROD, redirect Location was returned with STAGING url - so for some reason worker would follow it to origin behind that domain

Bit unexpected for me, since in front of domain there's worker, so why requests from worker to that domain are passed to origin