(click pictures to see animation of problem)

I've noticed that Sculpting characters with the Multires Modifier on leads to strange Material displays both in Eevee and Cycles.
Somehow it messes with the Base Color, Roughness and Alpha? Note how this only happens when "Sculpt Base Mesh" is disabled.
I tried reducing the scene to its basics and managed to replicate it on a simple cube.

I usually use 3.0 but have also tested it on the experimental 3.1.0, to the same results.

Here's the example file:

System Information
Operating system: Windows-10-10.0.19042-SP0 64 Bits
Graphics card: NVIDIA GeForce GTX 1070 with Max-Q Design/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 471.11

Blender Version
Broken: version: 3.1.0 Alpha, branch: master, commit date: 2021-12-09 23:43, hash: rBdffd032bc9b9

Short description of error
as stated above

Exact steps for others to reproduce the error

.Open attached example .blend file
.Select cube Object
. Make sure Multires modifier's Sculpt is on 1 and "Sculpt Base Mesh" is disabled
. switch from Object to Sculpt Mode
.notice how the material changes (takes on the background's color)