Do we need a feature switch? like a config variable.

AFAICT this already exists – $wgLogAutopatrol (see I418cc2fcc7).

That got abandoned until T184791: Make rc_patrolled 3-state instead of 2-state to distinguish autopatrolled edits is implemented.

Yes, but the config variable still exists, the abandoned change just updated the default value.

Yup, my bad. Sorry.

Nevertheless, this task can't be done until T184791 is done.

This is the investigation phabricator ticket, not the implantation one.

From yesterday's meeting:

How much work is needed

This will be my first thing for the next couple of weeks.

Do we need to remove data retrospectively?

If yes, does this need to be communicated and maybe decided after community consultation?

Yes, we will do it.

Do we need a feature switch? like a config variable.

There is already something like this and we don't need it

We need to remove old code after one release.

Yup

The maintenance script needs to remove old log entries and that needs to be added to update.php

Yup