Classical question: square brackets around tempo

I have a release of Mozart concertos. On some movements, there are square brackets around the tempo, like this:

Concerto in E-flat major, K417: I. [Allegro]

They’re not present on every movement, so I’m wondering if it has some meaning.

I suspect, based on the booklet notes regarding that particular track, that it might have to do with the fact that part of Mozart’s original manuscript is missing, so maybe his intention is not known. I also read in a forum discussion that it may mean that the composer didn’t indicate a tempo, so it is provided by the conductor/performer.

Does anyone here know?

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As far as I know a few movements of Bach’s Brandenburg Concertos have no original tempo markings, and tracklists often use [no tempo], [-] or [tempo_usually_played_in] (with brackets or parentheses) in that case: