13.3GB reserved by kernel sometimes on clean boot

[Paul Dev]

Description: Ubuntu 22.04.1 LTS
Release: 22.04
Kernel: linux-image-5.15.0-48-generic

Occasionally (twice today) a clean boot has left only 2GB of 16GB RAM usable.
Looking at syslog - its clear the memory is being reserved for some reason by the kernel:

Memory: 2558908K/16524372K available (16393K kernel code, 4377K rwdata, 10804K rodata, 3224K init, 6580K bss, 13965204K reserved, 0K cma-reserved)

Usually the amount reserved is:
Sep 22 11:35:57 pdlap01 kernel: [ 0.099454] Memory: 15926800K/16524372K available (16393K kernel code, 4377K rwdata, 10804K rodata, 3224K init, 6580K bss, 597312K reserved, 0K cma-reserved)

Been using linux on this device for years - only noticed since 22.04.1.
Both times today when it reserved 13GB - it was connected to the dell dock (dont know if that is relevant yet).
No recent changes other than security updates - but I noticed it did this a month or so ago too - but hoped it was a one off.

[Ubuntu Foundations Team Bug Bot (crichton)]

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