wudu n notices that something on the skin feels strange without knowing what it is, but they can see that the water is reaching the skin is the wudu valid? Even after washing it and while it was wet it still felt strange does that count as mixing with the water in a way that changes it properties

Ustadh AbdulAziz al-Haqqan

No this is extreme thinking that might lead to waswas as u have nothing on your skin blocking the water and when the water is poured it is water not anything else to assume that it has changed, but after it falls from your skin we don't pay attention to it.