A possible regression was found when rendering raster layers that use SLD files extracting contours (using WPS process gs:Contour) and a TextSymbolizer with a Halo.
The screenshots shows artifacts that are rendered on the top left corner of tiles generated by geoserver. These artifacts are only visible if a Halo is set for displaying the values of extracted contours.
Steps to reproduce :
Create a GeoTiff store with the given raster.tif
Add the two given styles to the created layer
Preview the created layer from geoserver with openlayer : use Tiled method for rendering (without tiled, there is only one artifact located on top left corner of the rendered image)
One can also add the following parameter to get a better view of the artifacts : &BGCOLOR=0x000000
Switch available styles to see that without the halo the artifacts are gone
This bug does not exists in GeoServer 126.96.36.199