The vacuum cleaner bag is not fitted.
The vacuum cleaner bag was fitted incorrectly.
A third-party vacuum cleaner bag was fitted.
The dust compartment can, if necessary, be cleaned using a dry duster, brush or, if available, a second vacuum cleaner to vacuum the dust out.

Insert the new vacuum cleaner bag into the holder as far as it will go, until you hear the bag click into place.
Leave the vacuum cleaner bag folded up when you take it out of the packet.
If you open the upper part of the vacuum cleaner, make sure that the vacuum cleaner bag is still seated correctly inside the appliance before you close it.
Even when correctly fitted, the vacuum cleaner bag (new or used) can be pulled out of its holder when the upper part of the vacuum cleaner bag holder is opened.
To check that the vacuum cleaner bag is seated correctly inside the appliance, proceed as follows:
Remove the vacuum cleaner hose.
Check the seating of the vacuum cleaner bag through the suction connection.

If the hygiene seal is open, the vacuum cleaner bag is seated correctly in the holder.

If the hygiene seal is closed, seat the vacuum cleaner bag correctly.