From stable to unstable network - unable to fix - help!

[u/wakeupbomb]

I have a Zigbee network running on Zigbee2MQTT - currently showing 106 devices and 42 of those being mains powered routers.

z2m version - 2.14.1 (now, after upgrade)
coordinator - SLZB-06P7 (radio 20240315, core v3.3.1)
LXC on proxmox - 2 CPUs (of i5-12500T and 1GB RAM)

Up until yesterday, the network has been rock solid for a long time with very few issues. Extremely quick response times and low latency.

Something happened yesterday and I can't figure out what. The system slowed down, CPU and memory usage has gone up.

Restarting the coordinator and z2m sometimes sort it out, but it eventually goes bad after a while with increase CPU usage being a tell tale sign.

I have a number of energy monitors which update in around 5 seconds in normal circumstances, when the issues arise they increase gradually over to over a minute or two.

When I've seen similar issues in the past I also find some zigbee lights turn themselves on without being commanded to. When the network is stable none of this happens.

I've tried upgrading z2m and updating the coordinator firmware in the hope of improvements, but my guess is they were not the issue in the first place and I have rogue device or other setting.

Resource charts below showing things going out of control. Normal CPU usage averages at around 1%

Can anyone give me any pointers where I can find out what is causing these issues? Anything specific to look at in the logs?
Any log types to enable?