Admitting the mistake before anyone catches it turns a scandal into a footnote.

Getting ahead of your own mistake changes what kind of story it turns into. Found by somebody else, it becomes about the hiding as much as the error, and people quietly stop trusting your reports in general. Said by you first, it is a thing that happened, got fixed, and stopped being interesting inside a day.

If something is wrong and you know it, say so today rather than after the weekend. Lead with the fix you are proposing instead of the explanation. The discomfort comes all at once and is much shorter than the other version.