• Version: 9.3.0
• Platform: Windows 10 64bit
• Subsystem: path

edit: See below comment for correct replication code

const path = require( 'path' );
const n = path.normalize( '../dir1/../../dir2' );
console.log( n );

Should output ../../dir2 but outputs dir2.

After some investigation it appears to have been introduced via commit b98e8d995efb426bbdee56ce503017bdcbbc6332 (path: fix normalize on directories with two dots)