I’m going to break this into 3 parts. All are independent of each other. Breaking it apart so none of it gets confused with each other.
PART 1
Can you clarify, is it your MacOS that is crashing? If so, could you please go to brave://crashes? From there, you should see some lists. Make sure to submit them if they didn’t already Send. Then respond here with your Crash Report ID (or a term similar, I forget the phrase).
PART 2
That part aside, when you go to Sync, you don’t have to choose Add New Device and all. You should be seeing options like below:
If you click on View Sync Code, it will open up a window that has the actual code. However, there will also be an option to choose View QR Code.
Try that and see if it crashes or if it’s only happening when you go through the Add New Device portion.
PART 3
This is seeming to be an issue with Spotify itself. You can check where people from all browsers are reporting experiencing this problem. Check out their support at https://community.spotify.com/t5/Content-Questions/Downtime-November-30-2022-Upstream-connect-error/m-p/5465551
People from Chrome, Opera GX, Firefox, etc are all posting with that error.
And it also was brought up here not long ago where it was investigated by person who helps with web compatibility. His response was: