Same issue for me also.
I found window.ApplePaySession.applePayCapabilities as undefined
While window.ApplePaySession.canMakePaymentsWithActiveCard and window.ApplePaySession.canMakePayments to be defined in the console
The official document states that applePayCapabilities requires - Safari Desktop 18.0+
Safari Mobile 18.0+
"applePayCapabilities" Apple Docs Link - https://developer.apple.com/documentation/apple_pay_on_the_web/applepaysession/4440085-applepaycapabilities
My MacOS version - Sequoia 15.0.1
Safari version - 18.0.1
Anyone how we can fix this, or is it something that we are doing it wrong?
Thanks for the help