Repro

1. scaffold a 1.8.2 project
2. swap to rush stack 3.3 for example

   npm i @microsoft/rush-stack-compiler-3.3 -DE
   npm un @microsoft/rush-stack-compiler-2.9 -D

3. run the upgrade o365 spfx project upgrade -o md -f upgrade.md

Current behavior

The report will suggest you to update rush stack 2.9, and if you follow blindly the instructions, you'll end up with two versions of rush stack installed.

Desired behavior

The report to suggest me to update the current rush stack I have or to suggest me to upgrade to the latest rush stack available.