If this source is to be believed, it's either going to Google or Tencent, but never both:
https://twitter.com/eromang/status/1183422784082530304/photo...
You can try yourself by going to one of the IOS Safe Browsing test pages on your phone, and when the warning pops up click "Show Details". It'll either say Google or Tencent on the warning message, which should let you know which one got chosen for you.
https://testsafebrowsing.appspot.com
I just tried it, and it says Google for me in the US.