To anyone using Sentinel-1 data:
The entire Sentinel-1 GRD data archive ( Sentinel-1 - Registry of Open Data on AWS) has been reprocessed to fix a GDAL bug affecting overviews (average resampling: “Starting with GDAL 3.1, this is a weighted average taking into account properly the weight of source pixels not contributing fully to the target pixel.” from gdaladdo — GDAL documentation). This affected overview levels whose size did not exactly divide the original image size; by extension the quality of data at these levels was degraded. Note that data at full resolution was unaffected.
As this was a significant issue and the archive is used by the community (it is not just us at Sentinel Hub), we decided that reprocessing was best for everyone.
Due to reprocessing this is no longer an issue and you can expect to get good data at all levels.