Since there is no objection, rfcs: parser as a go sub-module was accepted one weeks ago. You could check the progress and plan at pingcap/tidb#28257: Tracking issue for moving parser back to TiDB.
And now pingcap/tidb#28454: create the sub module has been merged that pingcap/tidb repo does not import code from pingcap/parser repo anymore. That means all further issues and PRs should be filed to pingcap/tidb repo instead. You should stop filing new issues and PRs to pingcap/parser. Changes in pingcap/parser will not take effect since all imports of parser was redirected to the local sub-module in pingcap/tidb.
Migration will be completed after pingcap/tidb#28700: fix compiling, add unit tests. We will soon started to clean issues and PRs in pingcap/parser repo. And all internal tools relying on pingcap/parser may start to change import path from “github.com/pingcap/parser” to “github.com/pingcap/tidb/parser”.