Proxy API questions

Hello. Where I can know about priority between Proxy API and abount:config proxy settings ?
And can you provide link to firefox source code about this priority?

The WebExtension Proxy API works separately and it doesn’t change abount:config proxy settings.

What will be in Proxy API if user set up proxy settings as manual PAC file? What settings will have more great priority - about:config OR pacScript in webextension?

The PAC Script in webextension should take priority