Why: I found a StackOverflow question stating that changing proxy settings at runtime is not supported and referencing an earlier issue (#244) that remains unresolved.
Stack Overflow

What can be considered to upgrade:

Ability to change network proxy settings at runtime (not only at initialization).

Expose CEF's request-context or preferences in Python bindings so proxy can be changed dynamically.
Possible title: "Allow runtime modification of network proxy settings in CEF Python (via RequestContext or similar)".