Huawei P Smart after update headphones quieter?

Have nen P Smart and since system update is the music volume when listening with headphones quieter I can somehow change that again?

So I guess it has to do with an update was previously much louder

on the headphones it is not connected elsewhere are also noisy

There are standards according to which headphones should not exceed a certain volume. To comply with the law, the manufacturer has probably limited the volume via update. You could try to find an old firmware version and flash it again.