Nice teeth marks, not!
With plastic parts like this, I often rely on the quality of molding to decide if it is or isn't playmobil. Your part seems to have some 'flanges' of spare plastic (non doubt there is a technical term for this!) inside the frames which is not often found on PM. That and 'Made in China' or 'Mattel' molded into the plastic are a good giveaway, IMO!
(Even if PM is sometimes made in China, they don't want to admit to this by stamping it into the parts!)