[Bug] Geographic (spherical coordinates) grid does not display correctly for polar stereo

[afrigeri]

Describe the bug Geographic grid does not display correctly

To Reproduce Steps to reproduce the behavior:

1. Create a location with this WKT:

PROJCRS["Moon2000_sp", BASEGEOGCRS["GCS_Moon_2000", DATUM["D_Moon_2000", ELLIPSOID["Moon_2000_IAU_IAG",1737400,0, LENGTHUNIT["metre",1, ID["EPSG",9001]]]], PRIMEM["Reference_Meridian",0, ANGLEUNIT["degree",0.0174532925199433, ID["EPSG",9122]]]], CONVERSION["Polar Stereographic (variant A)", METHOD["Polar Stereographic (variant A)", ID["EPSG",9810]], PARAMETER["Latitude of natural origin",-90, ANGLEUNIT["degree",0.0174532925199433], ID["EPSG",8801]], PARAMETER["Longitude of natural origin",0, ANGLEUNIT["degree",0.0174532925199433], ID["EPSG",8802]], PARAMETER["Scale factor at natural origin",1, SCALEUNIT["unity",1], ID["EPSG",8805]], PARAMETER["False easting",0, LENGTHUNIT["metre",1], ID["EPSG",8806]], PARAMETER["False northing",0, LENGTHUNIT["metre",1], ID["EPSG",8807]]], CS[Cartesian,2], AXIS["(E)",north, MERIDIAN[90, ANGLEUNIT["degree",0.0174532925199433, ID["EPSG",9122]]], ORDER[1], LENGTHUNIT["metre",1]], AXIS["(N)",north, MERIDIAN[0, ANGLEUNIT["degree",0.0174532925199433, ID["EPSG",9122]]], ORDER[2], LENGTHUNIT["metre",1]]] and this extents: projection: 99 (Moon2000_sp) zone: 0 datum: ** unknown (default: WGS84) ** ellipsoid: a=1737400 es=0 north: 1095700 south: -1095600 west: -1095700 east: 1095600 nsres: 100 ewres: 100 rows: 21913 cols: 21913 cells: 480179569

3. Add a geographic grid from the GUI, or draw it with d.grid -g for getting the current ellipsoid definition
4. Grid comes out like this:

Expected behavior A polar stereo grid

Screenshots If applicable, add screenshots to help explain your problem.

System description (please complete the following information):

• Operating System: OSX 12.5.1
• GRASS 8.2.0 (2022)