intercontinental

Very rare, but lens is WR and Red Badge so it should not happen with brand new lens. Maybe i'll try send it to Fuji service center. I had similar problem with new x-h2s which had a smudge visible on photos even on very wide apertures and send it to fuji becasue blowing and cleaning by swabs not helped. They change filter on the sensor under warranty and now everything is ok.

I sent lens to the fuji service center. They replaced fourth group of lenses under warranty.

Do you use f16 often?  There is little reason for this.  If yes, and you need it I'd consider service, if not then not.