I'm trying to make an Avios redemption booking from HKG to SIN using BA.com, and I am residing in Canada.

Upon selecting the flight (operated by CX), it charges me $102.77 per adult and $55 per infant for tax, fee and government charges, etc. When I look at the breakdown, it is only $47.77 per person for the tax, fee and government charges, so there is a $55 difference per person. (For infant, there is no tax but $55 charge that BA.com is charging.)

I thought booking on BA.com using Avios is free? Not anymore? Or does anyone know what this $55 per person charge is? I know if you're making a change or cancelling a ticket, they will charge you $55 US, but I never heard a online booking charge? Thanks!