When using Power BI Desktop to edit a DAX formula for a Measure, it's common to specify an existing measure. Taking advantage of the intellisense feature, you select some existing text (e.g. a SUM function you want to replace with a Measure reference) and type a left-square-bracket [, then a partial Measure name, then press tab to complete the entry.
Syntax error - you get an extra closing-square-bracket ] at the end. Huh? I didnt type that!
The issue appears to be that as soon as you select text and type the left-square-bracket, it automatically adds a right-square-bracket at the end of the selection. You usually dont notice this as your eye is naturally on the start of your selection where your cursor is.
Please stop intellisense from silently adding that closing right-square-bracket - it causes more problems than it's worth.