Quick comment; some distros have the OOM daemon set extremely aggressively (i.e. it’ll kill the process long before you consume all system RAM). Ubuntu had problems with this initially in beta testing of 24.04 if I remember correctly. Server distros tend to prioritise not having the system hard lock (which can happen on OOM)
Also some memory spikes are faster than user-accessible polling reads by default (or CryoSPARC reports). If a 1050 pixel box can consume 440GB+ in NU refine, it wouldn’t surprise me if 850+ is maxing out a system with 250GB. A quick test (not recommended for long-term deployment) would be create an 250GB swapfile on an NVMe SSD for that node, see if it breaks 250GB. Then you know you need an upgrade.