I’ve been thinking about this.
It may be your Mac is defective. It does happen.
As a former Apple Systems consultant, this is how I would proceed.
A. after each crash, go to the Logs folder in your Library folder (hold down the option key and select “Go” from the finder window"). If you sort by modified date in that folder, the top file should be called “Cubase (something).ips.” That contains the latest Cubase crash log.
You can right-click on that file and open it in a text editor. It’s easier to read if you change the font to a monospace font.
Search in that file for “crash”. It looks like gobbledygook at first, but if you read through it a couple of times, it starts to make sense. You can often find the culprit here.
B. Try resetting the SMC and the PRAM. It clears up a ton of wacky and odd behaviour:
Here’s how to reset PRAM on your Mac:
Shut down your computer and disconnect all USB devices (except wired keyboards).
Press the power button to turn on your Mac.
Immediately press and hold the Option, Command, P, and R keys on your keyboard. You need to press this key combination before the gray screen appears or it won’t work.
Hold down these keys for 20 seconds, during which time your Mac will appear to restart.
On older Macs that chime upon startup, hold down the keys until you hear a second chime.
For Macs with the Apple T2 Security Chip, hold the keys until the Apple logo appears and disappears a second time. Here’s a list of Mac models with the T2 chip.
Release the keys and let your Mac finish rebooting.
After zapping the PRAM or NVRAM, some of your user settings will also reset, such as keyboard layout, mouse tracking, startup disk, date and time, and volume. Check System Preferences and adjust anything that was changed. Otherwise, that’s all there is to reset PRAM on Mac.
(I would usually hold down the keys until there were 5 restarts)
Resetting SMC on Silicon
You can’t reset an SMC on Apple silicon, but some Apple forums have noted that shutting off your Mac and waiting for 30 seconds seems to work like an SMC reset. I would also remove the power cable too if you can. Can’t hurt.
C. You may have defective GPU / Video RAM or RAM in general, which can be hard to nail down.
If only the higher registers of RAM are bad or funky, you may only hit those regions when working on a huge project.
I would install a utility like iStat Menus (iStat Menus), which I’ve been using ever since it came out way back when. It will help you monitor CPU/GPU load, RAM usage, temperature, and a bunch of other things. It really helps one understand what’s happening inside your computer while you work. I install it on every Mac I’ve ever owned.
D. Try another DAW.
Perhaps Logic or install Reaper (as it’s kind of free).
Take note of how big your Cubase project is and try to replicate it in the other DAW.
Does the same behaviour occur? If yes, than it’s your machine; if not, then it’s something wacky about your install of Cubase (some plugin or something - I tried Mix Monolith a while back, and it crashed all the time. It never crashes with any other plugin)