Low memory warning, but tiny amount of RAM used on disk cache

Ok - ta - yeah, very on-brand for After Effects, I suppose..

I don't know what specifically will trigger this alert. I'm afraid it can be a lot of different things. I get this alert regularly, even with 128GB RAM and a 2TB ssd disk cache. There can be lots of causes, certain (combination of) effects, plug-ins, expressions, maybe a certain font used, other (adobe) apps running at the same time, complexity of the comp, using MFR, duration of uptime After Effects and/or computer, etc. Restarting AE will usually suppress the warning for a while. I would guess if you get this warning on a system with enough RAM available (32GB or more) there is some sort of memory leak going on in some process, filling up RAM, choking AE and it's memory management. 

No idea what changed between 23 and 24 that would change it for your projects, I had this warning also regularly using 23... My experience with this warning is also not consistent enough to pinpoint it to certain effects/plug-ins/etc. One day I'll have this warning, then I don't see it again for the same project while it gets more complex.

It's like AE is walking a tight RAM rope, sometimes getting severely out of balance, slowing down or even stalling all progress, and sometime just tripping up completely, leaving it hanging on it's crotch...

Ok - thanks for your reply - any ideas what causes that alert?  It's new since upgrading to 24 (along with frequent system crashes).

I'm Using 2023 for most of my critical projects and just attempting 2024 on internal projects till I work out why it's so broken on my macbook.

Unfortunately those are not really related. As far as I understand disk cache is used to store (intermediate) renderstates of frames, RAM is used for much more, including the actual calculations for the rendering and there are lots of effects and plugins that can trip and fill up the RAM.