That machine has feet, so it's not using the chassis of the current (Touch Bar) 13" MacBook Pro. It could be the current 14" MBP, the current 16" MBP or something new
That makes it one of three things (unless it's just a Photoshop job).
1.) A 13" "redesign" that is just putting a base M3 into the current 14" case (or a close relative - it might lose a port or two)
2.) A 13" redesign into a new chassis that shares some design language (including feet) with the 14" and 16" MBPs.
3.) Evidence of a new 14"/16" MBP (thereby a simultaneous release of M3/M3 Pro/M3 Max).
There are reasons to believe for and against all three. In favor of simply putting the base model in the 14" chassis is that the base model is due for an upgrade, the Touch Bar is all but discontinued (making the current 13" chassis unattractive), and using the 14" chassis is The Easy Way. Against that, the 14" MBP becomes quite confusing, since the base model is using a chip a step down, but also a generation newer, than the upgraded model. It becomes all the more confusing if a base M3 is anywhere close to the performance of an M2 Pro.
In favor of a redesigned base model, the 13" MBP is up for a redesign - it's an early 2020 design (the keyboard replacement came to the 13" MBP in May, 2020, and the M1 was essentially built in the final generation Intel chassis, which was only a few months old). I've never seen Apple just put an "up for a redesign" machine in another existing (and already mid-life) chassis. Against a redesigned base model, they don't really have anything very new that can do without encroaching on either the MacBook Air or the 14" MBP. They could do essentially a 13" version of the current 14" chassis, but that's pretty close spacing in display size (they have it now, but only because of the "leftover" 13" chassis).
In favor of a 14"/16" processor bump (in addition to updates at the lower end), "Scary Fast" suggests something beyond base models (someone pointed out that it was the tagline for the M1 Pro/Max). It would be a tough sell that updating the slowest machines in the lineup counts as "scary fast". If the M3 is enough faster than the M2 that the base models threaten the M2 Pro, that throws the MBP lineup into disarray (unless the Pro/Max machines are updated at the same time). If it's not, then "scary fast" means "updates to machines that aren't as fast as January's midrange laptop". Against a 14"/16" processor bump, it's awfully soon. It's not unprecedented - Apple occasionally releases updates (or machines that a buyer of the previous machine would have wanted to know about) very close together - but it's not that common.
I just looked up the chronology of all of this on EveryMac...
Original M1 (included the 13" MBP) - November 2020
M1 Pro/Max - October 2021.
M1 Ultra - March 2022
Original M2 - June 2022
M2 Pro/Max - January 2023
M2 Ultra - June 2023.
An M3 now would be around 16 months - close to the 19 month cycle from M1 to M2, and actually longer than the 15 month from M1 Ultra to M2 Ultra. Apple also likes to do Macs in October, and their next "we like to do Macs" window is around March.
The other consideration is that the iMac is an original November 2020 machine, approaching three years old. If they don't release the M3, and update the iMac to an M2, they it will be in the weird situation of having been updated right before a processor bump. If they release the M3, but ONLY in the relatively low-volume iMac, they just killed sales of all the notebooks for several months (if the M3 is any good) - many people will wait until the new processor is in their favorite Mac. They almost have to do some M3 notebooks (assuming that the "Scary Fast" invite is for Macs, which it almost has to be).
If the box is a fake, there's an easy release (and what I'd have expected) - all of the M3 Macs (or all except the Mini, since that is M2/M2 Pro), but NOT the M3 Pro/Max/Ultra models. If the box is real, the movement in the MacBook Pro line makes things a little more complex...