If render settings resolution scale had lowered resolution, cached
images from render image/animation session could "stay around"
and be incorrectly used in the VSE preview area. Two cases I found are
fixed here:
- Intra-frame cache was not flushed upon actual final resolution
change,
- "Source images" for effect/scene strips were not removed when
requested resolution no longer matches their rendered resolution.
Pull Request: https://projects.blender.org/blender/blender/pulls/141297