I had a problem with pixelized embedded thumbnails in JPG and couldn’t figure out where the issue was. In the end, changing the camera resolution from 4080 × 3072 (85:64, 12.53MP) to another resolution helped. To fix already existing pixelated thumbnails, there is an application: https://github.com/stefanoltmann/thumbnail-fixer.
I had a problem with pixelized embedded thumbnails in JPG and couldn’t figure out where the issue was. In the end, changing the camera resolution from 4080 × 3072 (85:64, 12.53MP) to another resolution helped. To fix already existing pixelated thumbnails, there is an application: https://github.com/stefanoltmann/thumbnail-fixer.