In the following environment,

Web API --(https)--> APIcast --(https)--> Squid --(https)-→ APIbackend(external) 

when proxy is set by Proxy Service policy, API request always works against https backend even if :

• in APImanager CR, set openSSLVerify: true

spec:
  apicast:
    openSSLVerify: true
    ...

• in upstream mTLS policy , set _ verify: true _with invalid ca_certificates

When invalid ca_ctificates is set in upstream mTLS policy, API request fails if proxy is not used, but it works if proxy is used.