From what I saw Cosmic has a lot of potential and looks pretty sleek too, right now I'm using KDE it's a great desktop, but now that I have a second monitor it randomly crashes on me, I think I'll switch to Cosmic when it reaches beta.
Well, since Cosmic isn't going to be ready for a couple years yet, let's try to fix your multimonitor issue. Are you running on Wayland and what's your GPU?
I'm guessing that's the onboard AMD graphics then?
If you do an lspci -k | grep -EA3 'VGA|3D|Display' what does it return? Are you able to find anything in dmsg (journalctl -xb-1 for previous boot log) that would give an error message to investigate?
here is what I got 04:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Mendocino (rev c2) Subsystem: Lenovo Device 380e Kernel driver in use: amdgpu Kernel modules: amdgpu
I don't think I understand what I'm reading but here is all the error I could find: https://rentry.org/gni28ogy
Might have to get the full log, and it should be from immediately after one of those unexpected reboots. The flag b-1 indicates journalctl to export the logs from the previous boot (-1) instead of the current log. So if you do sudo journalctl -xb-1 > log.txt after one of these reboots and paste that file to look at, we might get something useful.
I'm fairly confident that's a problem that can be fixed with having an AMD graphics driver running. If it were nVidia, I'd be less confident.