GDAL: wrong corner coordinates from KNMI grib file

I’m trying to parse KNMI grib files to extract weather forecasts for The Netherlands. I use gdal.netcore which is a .NET wrapper for gdal 3.2.0. On the website of KNMI they say the following:

• Rekenrooster: Lambertprojectie
• Product resolutie: 0,037° west-oost en 0,023° noord-zuid (300×300 punten)
• Grid representatie: Regulier Lat/Lon
• Gebiedsdefinitie: noord 55,877° N.B. zuid 49,0° N.B. / oost 11,063° O.L. en west 0,0° W.L.

However when I run

var info = Gdal.GDALInfo(dataset, new GDALInfoOptions(null));
Console.WriteLine(info);

I get the following information:

Driver: GRIB/GRIdded Binary (.grb, .grb2)
Files: /home/HA40_N25_202103190600_00000_GB
Size is 300, 300
Coordinate System is:
GEOGCRS["Coordinate System imported from GRIB file",
    DATUM["unnamed",
        ELLIPSOID["Sphere",6367470,0,
            LENGTHUNIT["metre",1,
                ID["EPSG",9001]]]],
    PRIMEM["Greenwich",0,
        ANGLEUNIT["degree",0.0174532925199433,
            ID["EPSG",9122]]],
    CS[ellipsoidal,2],
        AXIS["latitude",north,
            ORDER[1],
            ANGLEUNIT["degree",0.0174532925199433,
                ID["EPSG",9122]]],
        AXIS["longitude",east,
            ORDER[2],
            ANGLEUNIT["degree",0.0174532925199433,
                ID["EPSG",9122]]]]
Data axis to CRS axis mapping: 2,1
Origin = (-0.018500000000000,55.888500000000001)
Pixel Size = (0.037000000000000,-0.023000000000000)
Corner Coordinates:
Upper Left  (  -0.0185000,  55.8885000) (  0d 1' 6.60"W, 55d53'18.60"N)
Lower Left  (  -0.0185000,  48.9885000) (  0d 1' 6.60"W, 48d59'18.60"N)
Upper Right (  11.0815000,  55.8885000) ( 11d 4'53.40"E, 55d53'18.60"N)
Lower Right (  11.0815000,  48.9885000) ( 11d 4'53.40"E, 48d59'18.60"N)
Center      (   5.5315000,  52.4385000) (  5d31'53.40"E, 52d26'18.60"N)

This is quite close (55.8885 vs 55.877) but nonetheless inaccurate. Even if I try to project it, it still shows the same coordinates.

GdalBase.ConfigureAll();
using var dataset = Gdal.Open(@"D:HA40_N25_202103190600_00000_GB", Access.GA_ReadOnly);
var info = Gdal.GDALInfo(dataset, new GDALInfoOptions(null));

Console.WriteLine(info);

double[] adfGeoTransform = new double[6];
dataset.GetGeoTransform(adfGeoTransform);

var upperX = adfGeoTransform[0];
var upperY = adfGeoTransform[3];

var lowerX = upperX + (dataset.RasterXSize * adfGeoTransform[1]);
var lowerY = upperY + (dataset.RasterYSize * adfGeoTransform[5]);

var projection = dataset.GetProjection();
var source = new OSGeo.OSR.SpatialReference(null);
source.ImportFromWkt(ref projection);

var target = new OSGeo.OSR.SpatialReference(null);
target.ImportFromEPSG(4326);

var transform = new OSGeo.OSR.CoordinateTransformation(source, target);
double[] data = new double[3];
transform.TransformPoint(data, upperX, upperY, 0);

Console.WriteLine(data[0].ToString() + " " + data[1].ToString());

So what am I doing wrong here?