I had a 21 M3P that I got in March, crashed it in February, just got my 23 M3P which was produced Feb15, 2023.
1)The ultrasonic sensors on the front and rear bumpers are gone, no little white dots. (Personally I think that kind of sucks, I get bad distance measurements when backing into my garage and not great sentry mode alerts since it won't see people when it's raining. On the flip side it looks way better from the outside, but hey it saves tesla a headache and money, Not us.)
2) people are saying the ride height is different, I disagree, part numbers are the same for both suspensions, it just doesn't say lower on the website. (Seems the same argument as how many licks to the center of a Tootsie pop in digging deeper though) and suspensions do settle over time, so it's not fair to look side-by-side at a 2 year old car, next to a brand new one.
3) interior door panels are different suede arm panels, instead of white (or interior option), and updated top part including a white strip accent.
4) rear doors have relocated speakers I think? (I never rode in the back of mine but I didn't notice the tiny speakers in the doors before.
5) AMD processor (I remember hearing it's 10x more processing power, idk for sure though)
6) all door pockets front and back now have a light inside them that dims with screen brightness.
7)"matrix" headlights like E90Alex said
8) 16v lithium (accessory battery, instead of 12v "lawnmower" battery)
The primary battery is supposed to be the exact same 2170 type Lithium-ion, Nickle-Cobalt-Aluminum. (Arguably the most efficient battery they have, over the 4680).
Driving the new one I've noticed two things, it's ever so slightly better wh/mile, and the Regen braking is a bit more pronounced at higher percentage charge levels than my 2021 M3P.
Build quality (panel gaps, and missing rivets, mismatched white/black bolts) is slightly better in the new one, but neither was bad in any significant way.