Two easy ways to make my beta 3 crash

Hello,
On my MacBook pro 15 2019 / Big Sur, I found 2 ways to make crash Resolve, and even make the system down!
First is easy and frustrating : in color, if I try to add the new Relight effect on a node ( with a Blackmagic raw footage ), Resolve freeze for a while then crash, and computer come back to "opening session"
Second way : if I try to apply the "2X Enhanced" superscale in the clip attribute of a movie made with a DJI cam in 4K mp4 ( which I guess, is probably not a good idea! ) the result after a few seconds of freezing is a crash of Resolve and the OS...
May I figure that my Big Sur OS and my "old" 2019 Mac with only 16go ram could be responsable?

I'm afraid you're guessing right. I can use both FX without crashing, but they are sloooow.
Is DR 18.5 certified for Big Sur at all? And then, how much VRAM in your laptop's GPU?

My Radeon has 4 go ram...

Well, that might explain it. It's not only the VRAM, but also the older Radeon. In those times, Apple was falling behind regarding graphic power in laptops and only recently took the lead again.

I admit that DR shouldn't simply crash, but tell you the hardware is insufficient for those specific tasks. If you wan to just try out the new possibilities, a 1280 by 720 timeline might work. But for any serious work, you'll need a new machine,

I tryed to use relight with a 1280/720 Prores footage. Same result, DR is freezing the computer for like 20 sec, then crashing along with the system...
I can agree my 15' 2019 MacbookPro already belong to prehistory, but still it should not be a normal reaction...

Relight, just like Depth Map, Magic Mask, Speed Warp or the like, belongs to the heaviest effects you can ask from any GPU. Try something milder, like editing, transitions, and ordinary grading.