PayPal subscriptions and one-click upsells
PayPal buyers were your easiest first sale and your hardest second one. Every upsell sent them back through PayPal to approve again, and a subscription sold through PayPal had nothing to renew with.
The enemy is asking a buyer to log in twice to give you more money.
PayPal checkouts now save the buyer's wallet with the first order. Subscriptions renew against it on schedule, and failed renewals go through the same dunning as card renewals. Upsells become one click: the saved wallet is charged directly, and when there is none the upsell falls back to the usual PayPal approval.
Saving wallets has to be enabled on your PayPal app. ElasticFunnels checks this when you save the PayPal merchant and tells you if it is off.
Try it: save your PayPal merchant, buy a subscription product with PayPal on a test funnel, then take the upsell and confirm it charges without a second PayPal window.