I noticed that last.fm artwork grabber only gives the down/upscaled 300x300 artwork instead of the original version of the uploaded artwork on last.fm.
Currently i use Album Art Downloader to get the last.fm artwork which does get the original uploaded artwork from last.fm but downloads the uncompressed png most of the time. There's a jpg version of this but it's noticeably compressed like it's saved via paint.
If the last.fm artwork grabber can be changed, i would like it be change so that it grabs the original artwork instead of the 300x300 version. If musicbee can convert png files to jpg it would be nice if it's downloading the uncompressed png version and convert it to jpg with less compression. If not, the grabber can download the compressed jpg version.