What could be the descision process of +/- features for Chrome

Hi friends,

I wonder how internally project managers and other leaders vote for adding/killing features?

The question comes from the confusion that on version 91 it's no longer possible to turn off the custom windows toolbar by using the flag --disable-features=Windows10CustomTitlebar (there is another one but doesn't work either).

Essentially my question can be break down to two parts:

Part 1 - Who and why the custom toolbar is decided to be added? As a customer can we actually find the one responsible of adding this feature into Chrome? Was it because of popularity (e.g. Microsoft likes to build new features based on customer votes, sort of) or other reasons?

Part 2 - Who and why the flag is disabled for version 91 (at least the most recent sub-version)? With the flag users have the option to opt out of the feature, but why disable it?

BTW, in case that the original example is wrong, i.e. I can still use some other flags to turn it off, I think the question itself is pretty solid.