By Foo Yun Chee BRUSSELS (Reuters) – OnlyFans, an online platform known for adult content, should pay UK value added tax (VAT) on the full amount paid by subscribers to content creators, not just its 20% cut of the fees, an EU court adviser said on Thursday. Founded in 2016 and with more than 100 million users, OnlyFans flourished during the pandemic as a way for creators to earn money by selling content directly to paying subscribers. OnlyFans operator Fenix took its grievance to a UK tribunal after UK tax authorities ordered it to pay VAT on all the money paid by fans, not just the 20% it to…