Is Qubes-OS wiping ram by default on shutdown?

Hello ! I’m trying to protect myself from Cold boot attacks, and so wipe the rams on shutdown, to avoid any leaks.

Wipe RAM of VMs synchronously when shut down and killed #1562

from above link:

marmarek commented on Sep 14, 2019
On memory balancing, the memory definitely is zeroed before returning it to Xen. On VM shutdown/crash/etc it is too, but I’m not sure if it’s done synchronously, or asynchronously - IOW at which point in time it is guaranteed to be cleared already.

also from last comment on the link:

also related:

I don’t think you can rely on shutdown to zero the memory, someone trying to do a cold boot attack wouldn’t shut down the system, they would hard reset the system.

You could look into memory encryption, I think it might be able to protect you against an attacker that has the ability to cold boot the system.