I built one project with 3.8.0.1641 (MGCB and MG in Visual Studio 2019) and one with 3.8.1.303 (MGCB and MG in Visual Studio 2022) and got these results:
Identical SpriteFont file in both environments; referencing Arial at size 50 and built using Color TextureFormat instead of Compressed
To my surprise, when I tried to use the built SpriteFont xnb from 3.8.0 in my 3.8.1 build, it seemed to just work. I had thought in the past I got an error when attempting to do this saying the content was built with the wrong version of MGCB.