Upper/Lower 4 day split help

Ive been doing a 4 day split ever since I started working primarily due to time constraints in my weekly schedule that makes it really tiring and ineffective for me to do 6 days like I used to for PPL.

Currently I do 2 exercises with 3 sets per muscle group(6 a workout, 12 sets total week) and it feels like I’m slowing down on progress. Wanted to ask for some advice or help here on how you guys structure your upper/lower days and still see progress both in the gym and bathroom mirror