Well, no the load of the machine is usually fully covered by the amount of surface provided by the brushes. The spring pressure of the brush assembly keeps them well pushed to the collector. But the spring tension is getting weaker, the shorter the brushes get - so this leads me to the conclusion the brushes should be replaced soon, as the sparking is most probably causing serious heating of the brush assembly and motor Collector. In excess this could burn down the collector - weld the brush assembly to the collector - requiring an expensive change of the motor.
So i would seriously recommend to inspect the brushes and replace them.
Festools great Service can be of help here, not only for supplying the brushes, but also with replacing the brushes and doing a complete inspection of the device.
Cause is suspect, if the brushes are worn down, maybe there are also other mechnical parts (bearing, rods) which require maintenance.
kind regards, Mike