Paul Scholes was rumoured to be an Oldham fan. He denied it. Nicky Butt was rumoured to support City. Giggs grew up a Cardiff fan. Joey Barton supported Everton. Leighton Baines supported Liverpool. Danny Welbeck was an Arsenal and United fan though he played for them both in the end. Ravel Morrison was and still is a Gooner. I think Bale supported United. Rio Ferdinand supported Liverpool. David May was a City fan. Kenny Dalglish supported Rangers. Fowler, Mcmanaman, Owen and Carragher supported Everton. Luke Shaw supported Chelsea. Jadon Sancho supported Chelsea. Wan Bissaka was Arsenal I think, not sure on that.
Recency bias. Sports is a what have you done for me lately business. People forget a teams result last week never mind 2 decades ago.