Does this occur at maximum turbo power? Because in the highest suction mode, all these hoovers are usually not able to run for long. But if this occurs during normal vacuuming, I would charge the battery for a longer period of time, because in normal suction mode the power should last up to 60 minutes, as specified by the manufacturer.

A sudden drop in performance could also indicate a damaged cell in the battery, which I would then report to the support team.