How do I increase the 'stolen memory size'?

Nov 13 18:29:35 Cogsworth kernel: [39625.205645] i915 0000:00:02.0: [drm] Reducing the compressed framebuffer size. This may lead to less power savings than a non-reduced-size. Try to increase stolen memory size if available in BIOS.

So - IS there a way to increase the ‘stolen memory size’ in the Framework BIOS? Do I need to update the BIOS?

I’ve got full memory (two channels), so I don’t think ‘External monitor flickers constantly’ applies, though I am using a 4K external monitor and DO experience intermittent flickering.

Digging around with the info on how to look in to GUC performance and logging and will report any interesting bread crumbs.