If with full logging enabled /var/log/syslog does not contain anything related to the crash, then the system did not or was not able to log anything .
The kernel did not change for a while, and you say you face the same on the old Buster image, so it must be triggered by something specific to your system/setup (not ruling out that it could be solved kernel wise as well).
Do you have any USB devices or other peripherals attached, aside of the screen? It seems to be triggered by high system loads (PyNaCl build), so a power/voltage issue is what we may look for. I remember that the N2 (with official Hardkernel kernel) generally has issues with USB, so probably it does not handle power draw from USB devices properly which leads to an undervolted/unstable remaining system in case of peaks.
Topic bookmarked . Odroid N2 (N2+ 4 GiB) arrived yesterday, started testing yesterday, will continue today with media/GUI and overclocking. When all done with the old image, I’ll repeat with one based on Armbian kernel, so we can compare results: https://github.com/MichaIng/DietPi/issues/5039
New image based on mainline kernel is available since a while. Based on my testing it works more stable indeed, i.e. while the old one crashes on heavy load with highest CPU frequencies applies, the new one runs rock solid with those frequencies. Also kernel errors are less. Sadly old systems cannot be upgraded, hence the new image needs to be flashed freshly.