Hi there, welcome! Benvenuto 
From my limited technical knowledge, but with good memory, I can say that unfortunately these are very difficult cases to troubleshoot.
The first thing I would say, since the system is up-to-date (and also the BIOS) is to try other Kernels, maybe starting from the LTS one.
Going into more detail, maybe it would be useful to collect logs at sleep time, but here maybe those who know more than me will ask for more details. For example what kind of sleep you use (see also ref. below).
In the meantime I refer you to the Arch Wiki page, to see some suggestions, especially in the troubleshooting section.
It is recommended to try other kernels for example, and to verify the early KMS start via the parameters in /etc/mkinitcpio.conf. In your case I imagine i915 is there; to verify the Nvidia part I think nvidia, nvidia_modeset, nvidia_uvm, nvidia_drm.
https://wiki.archlinux.org/title/Power_management/Suspend_and_hibernate
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