Major artifact when upsampling with Average

[jdries]

Describe the bug

The following result was obtained when upsampling a COG to higher resolution, using 'Average'. I'm aware that doing upsampling with this kind of method may not really make sense, maybe the artifacts are even the expected outcome somehow.

To Reproduce

I don't have a small sample yet, but the more extensive test does this:

• start from sentinel-2 utm data as COG
• load with GeoTiffRasterSource
• resample to webmercator, zoom level 14 so higher than original resolution, using Average

Expected behavior

Not

[pomadchin]

Ugh sadly we need a reproducible example + the exact code used.