Does the white spot behind the ear constitute a barrier preventing the water of Wudu from reaching the skin, given that this area is not obligatory to wash during Wudu, and are my past prayers valid or void?

Wiping the outer part of the ears that is attached to the head is included in ablution, as this has been authentically reported from the Prophet, peace and blessings be upon him. The ablution and prayer of the questioner are valid even if there is a barrier on his ears preventing water from reaching them, as the validity of ablution is not affected by omitting the wiping of the ears, whether intentionally or out of forgetfulness. This is the opinion of many Hanbalis and the consensus of the jurists.