Don’t run either Firefox or VSCode add-ons. Just using Mosquitto, File Editor, Samba, SSH & Terminal.
I don’t know if the crashing is reliable enough to check it with Mosquitto enabled or Safe Mode, but I’ll see what I can find.
My RPi3 has 1GB RAM. Total usage peaks at around 85% and Mosquitto claims to be using around 3%.
Very similar to Mosquitto broker restarts every few minutes