Kindly refer to the following link(s):
Performing wudu when wearing hair gel or oil | Assim Al Hakeem
Making wudu over hair gel or oil | Sheikh Assim Al Hakeem
Can we make wudu with Oil or Gel on our hair?
Is my Wudu and Ghusl valid if I apply Hair Gel?
Must we remove beard oil / cream or hair gel / cream when performing wudu?