As part of media analysis and as called out within this support document Default Artwork is something that is created: https://support.plex.tv/articles/200289336-analyze-media
Generate Default Artwork:
- During analysis, artwork will automatically be grabbed from a video file. A background image will be pulled out as well as a smaller image to be used for poster/thumbnail type purposes. In most cases, these won’t actually be used and downloaded metadata artwork will instead replace them. However, they’re available as a fallback for situations where downloaded artwork isn’t available.
Request:
This generation of default artwork is really something I wish we could disable. All my media is accurately named and 100% matched so I never need to fall back to this default artwork which plex auto creates during analysis. The generation of GBs of this data is redundant, wasteful and frankly just not needed.
An advanced setting to disable this part of analysis would be really nice to have.
BTW… can’t vote for this suggestion due to the forums 5 vote rule 
