Just a little follow up. The author of node-red-contrib-ftp-server has updated it to work with 8.x, but apparently the nodejs ftpd module is not working with 10.x.
I’ve upgraded node-red-contrib-ftp-server and nodejs to 8.x and if anything the leakage is a bit worse than with v4.9.2, but in any event its not a serious problem as after node-red crashes for lack of memory systemd restarts it in a a few seconds which is inconsequential in the overall scheme of things since my Lorex DVR has a 4+ second latency between triggering and sending a snapshot.
Its been running great despite the periodic crashes and restarts. I hope to try reducing the the --max_old_space_size=256 paraneter this weekend to make the garbage collection more aggressive. I hope my understanding of this parameter is not reversed 
