Have your Apple AirPods Pro ear tips broken? Then this problem may be common.

If Apple's original silicone ear tips have broken, it is common for there to still be a piece of them left on the headphones that you need to remove in order to put on a new pair of ear tips. See picture below of this white plastic part that needs to be removed.

Have the ear pads on your Apple AirPods Pro broken? Then you may need to remove this.