A bar showing a download at sixty percent describes work moving towards completion. A bar showing a container sixty percent full describes a measurement within a range. Similar shapes do not give the values the same meaning.
HTML provides separate elements for these purposes. MDN describes progress as task completion and meter as a scalar measurement within a known range.
Ask what reaching the end would mean
In an invented upload interface, reaching one hundred percent could mean the file transfer stage is complete. The service might still need to process the file. Label the stage instead of letting the bar imply that every later step has finished.
For a storage meter, reaching the maximum means the measured capacity is used. There is no necessary expectation that the value should keep rising towards a successful finish.
A progress indicator can also be indeterminate when the amount remaining is unknown. Replacing uncertainty with a made-up percentage gives a more precise-looking but less truthful interface.
As a reader, check the label and unit. As an author, supply an accessible name and useful text explaining the stage or measurement. Colour and animation alone should not carry the distinction.
Editorial illustration from this site’s image library; not documentary evidence of the example or object discussed.