Compression can introduce visible defects around text, edges, and areas with subtle color changes. Recognizing those defects helps you distinguish a damaged export from a composition problem.
Inspect the vulnerable areas
Look near small letters, hair, repeated patterns, and high-contrast borders. Blocky patches or faint halos may come from encoding rather than the original scene. View the file at normal size as well as magnified; extreme zoom can exaggerate issues that viewers will never notice.
Compare with the source
If you have the editable original, export a less compressed copy and compare the same area. Avoid repeatedly opening and re-saving an already compressed image as your main editing workflow.
Fix only what matters
Prioritize defects that reduce recognition or readability at the actual display size. A cleaner source photograph or simpler text treatment may help more than increasing file size alone. Save a fresh export from the original project whenever possible and keep the downloaded reference unchanged for comparison.